[...] sure "at some point in the future", Soft would inevitably start having issues on newer setups,
when Virtual Machines would come into play.
*Yet*.. when do you think would that be?
Soft runs just fine on Win8, and would surely still run fine on the Win9 which is itself for some time down the line.
... if not also the OS after that.
(os ver. coming out every couple of years, quite consistently with 3 versions back compatibility modes)
So we're looking at at least 8, if not 12+ years.
On top of the fact that people rarely switch to new OS'es very rapidely,
like so many are on still on Win7 which many perfer to win8
(new, absolutely is not always necessarily better)
And there will also be the advantage of anything made to work with 2015 will work as long as XSI works.
(no previous version incompatability issues)
And at some point, Exocortex, Mootz, and other plugins would not surprisingly become either more accessible if not free...
Which would make it yet more "killer" than it already is.
And if for any reason there would eventually be licensing fails, it would by then be quite legitimate to just use cracks.
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But similarly otherwise, concerning the Future, (concerning those that can choose what they use)
when would you think something will surpass SI's general strengths?
And/or rather -what- will it be...
If Maya could have potentially been a closer replacement overall, it would have involved making quite a few changes
in areas that hasn't been touched since even before the last FXTree Update,
and it would be quite unrealistic to think that such changes would ever happen.
So that leaves the introduction of new players.
May it be releases of production studio software,
Pixar Premo?, .. Dreamworks Apollo?
Buf's own is suppose to come at any time early this year..
(any/all of which, "production/artist friendliness" seemed to have come -first- from the very start)
Or... that some new thing comes out of the blue
(not unlike the new FlowBox Comp package)
Also look at Exocortex Clara.io, who made a basic yet more than just functional online DCC all within a really short time, with usability that feels alot like a hybrid or "the best of" Softimage and Max .
... it might even be a 3rd party making a DCC out of Fabric (since Fabric won't (.. ever want to compete with Maya))
So who (the heck) knows.. but if you ask me, it would be pretty astonishing if some (far) more comparable options wouldn't be coming (way-way!) before Soft would actually stop running just fine,
especially with just 1 (one) non-specialized/general-purpose (and rental only) DCC considered to be "HighEnd", the void is just screaming to be filled.
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But until then, concerning longevity, we recently spoke of Eddie, but this all SO reminds me of exactly EDDIE.
Where we only realized how good it was until... well at least Windows is unlikely to go bottom-up anytime soon.
With a feature-set and/or subtle qualities that made it YEARS before it's time.
Enough to make me say..
<< Would love to use it on a box with more than 500mb of ram

(and higher than 8 bit depth) >>
Well, it seems that it did have 16bit depth..
Also,
"Softimage Eddie supports network batch rendering, 32- and 64-bit multi-processing, and an open plug-in architecture for custom tools."
So on a fast machine with not even that much ram, (after all this time) I would have choosen Eddie as it was,
*definitely* over Shake (10 Years later) , AfterEffects (then -OR- now),
and .. also over Nuke today?
Well it would actually be a hard decision(!) only because of floating point.
(only for when dealing with values going over "1", in which simple tricks can be used to easily go without, similar to using Photoshop in 16 bit mode)
Meaning, it would not be by nostalgia that would make the decision hard,
it would be because it was really quite exceptionally Streamlined, Efficient, Straight-Forward while being uniquely advanced.
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Apart from the things formally posted, it also had color matching tools that with a few clicks,
whatever you were integrating simply fit with your background.
An NLE timeline (3.5) where you could sequence comp trees together,which is another thing that Nuke only very recently finally had (in the Deluxe ver. of Nuke 9)
Nuke now has a pretty good Vector paint, but Eddie's paint would still be way(!) more sophisticated hands down, it was an entire program on it's own.
And memory management was remarkable (by sheer necessity back then)
You would work with 2k plates with trees spanning several pages, and it would constantly save caches, flush, and go-on with a couple other nodes..
So It would sort-of always take -all- of your (comparatively insignificant amount of) memory or whatever remained of your 128-256Mb of ram, and satisfy itself with that, and just keep chugging along just fine.
So with 4-8-16 Gigabytes... it would be quite something.
While most Software typically become sssllooowww at best, if not almost basically stop running, if memory limit is reached
(very much including hungry-hungry Nuke, which can basically -only- go through -all- nodes -all- the time)
And apart from it's bullet-point features, the working experience with it was remarkable, only because of tons of little things, or because of extremely refined workflow details, as if everything has been thought-of and thoroughly tested, making it extremely sturdy and fluid, you could tell that it was developed right along people that used it every day (also ring a bell?) if not being comp artist themselves, over at AnimalLogic.
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Also Eddie, was the literally the first, and has been the (software only) basis, reference, or parent, of subsequent *Discreet*Logic solutions, to which have historically been the only things that could more closely match it.
Eddie's history itself is all intertwined between Soft, Animal-Logic, Discreet-Logic, and then back to Soft again, and including TheFoundry.
Discreet Logic was founded in 1991 by Richard Szalwinski, former director of sales for Montreal-based Softimage, along with two Softimage coworkers, Simon Mowbray, and Diana Shearwood. Discreet Logic's first business was as a licensed distributor and developer for Eddie, a two-dimensional software program developed by Animal Logic Pty. Ltd. Eddie was associated with Australian software engineer Bruno Nicoletti, who later founded visual effects software company The Foundry, in London, England. In 1992, Discreet Logic entered into a European distribution agreement with Softimage, and shifted its focus on Flame, one of the first software-only image compositing products, developed by Australian Gary Tregaskis.[2] Flame, which was originally named Flash, was first shown[3] at NAB in 1992, ran on the Silicon Graphics platform, and became the company's flagship product.
By the way, while Autodesk may have only mostly "maintained" Flame, plus or minus some nice or okay things, Flame has mostly remained 90% of what it was, that fact similarly in no way takes away any of it's own (non hardware related) still very current and real awesomeness.
Nevertheless, the point is, if Eddie wasn't exclusively on SGI's, it would *absolutely* still be one of the most refined, if not -the- most refined and (both major and micro-)feature-rich on many fronts.. after ~20 years (!)
How do you explain that? Time-travelling developers? Magic?
well.. define "Magic".. (passion)
As Stephen also noticed, I couldn't even find a decent screenshot,
which may have to do with the fact that it was mostly before the internet.
Crop from one of Stephens FlashBacks ::

I personally took those screenshots for marketing by the way
But you know.. as long as they can run, Really Exceptional software don't become old,
they very much become timeless proportionately to their goodness,
not unlike any really good song from any time, they just stay really good!
Does this (below) look like "old software" ? lol ;)
(impressive bullet-point list which still barely makes justice to what made it what it was but..)
Just look at those paint features, and/or pretty-much any other section.. talk about "timelessness"
But in any event, XSI can also *absolutely/definitely* -- in very much in the same way and for the same reasons -- qualify as one of those timeless and exceptional masterpieces.
(with it's Passes/overrides system, Non-Destructiveness, ICE, a, very good/intergrated 2D side to it, Everything working with everything, Fast Easy and intuitive, tons of very refined workflow subtleties etc... etc... and while it can play well with others, it's also entirely complete, integrated, and self-sufficient )
So all that, except running on a pretty sturdy platform this time, while having been made current to the very latest OS,
until what could more easily qualify as the "next best thing" comes around.
So SI becoming "outdated"? Hum... ;-]
Cheers & Merry Christmas!