(Like the PSX version of WZ seemed to limit the engine a lot, eg. a FRACT type was needed, because the PSX didn't support floats.)
iirc, the psx used an arm processor, and those generally are very slow with floating point numbers -- suffice it to say, the programmers could've used a float type (even if it was emulated, as is the case on some arm processors), but it's a whole lot faster to use something integer based.
And: How long till the XBox will be so outdated that Warzone (with the new features) doesn't run on it anymore smoothly?
i don't really see that as a good reason not to make a port -- it'd be the same as asking "what about all the people with pc's that are currently capable of running warzone but aren't good enough for the features we have planned?"
one of the main graphical improvements created by the dev team (shadows) can be turned off, presumably decreasing performance when off. if most new graphical features can be turned off, then it's not really any issue, since, at least the graphics can eventually improve past where they are now (on the xbox, you don't see many titles come back and offer patches that increase the graphics), and hopefully, most of those features can be turned off
say we eventually add fluid physics: rain falls down, hits a hill, and begins to flow down to lower ground... then we make that effect interact with gameplay: the hill becomes muddy, and tanks rolling across it might slide down as they drive over it, and going uphill to attack an enemy base is considerably more difficult in a rainstorm than it already would have been -- in either of these cases, the visual effect of water flowing down a hill could still be turned off, while still providing the gameplay interaction, and even the "slide calculations" could be done server side in a multiplayer game (which is ideal - too much client side and people cheat, and the only effective
anti-cheat protection is making the client entirely unauthoritative), further lightening the load on the client in some cases.
there might, of course, be some graphical/gameplay improvements that can't be turned off, such as replacing the tile system with a nice free-flowing mesh -- there's no way to effectively make this work again as a tile system, and the processing power would go up.
so indeed, whether or not this game eventually has half-life 3 style graphics, we should try to make as much of it as possible old-hardware friendly, in which case, the xbox would be viable for some time: the xbox is far more capable than the minimum computer needed to play this game originally, and unless something has changed, afaik, the dev project enhancements, with shadowing off, should be perfectly playable on the same machines as could play it when it was still closed-source.