I imagine we'll see a bump to the maximum amount of anti-aliasing and isotropic filtering options, textures will probably be bumped to a more HD friendly resolution. I imagine we'll also see nicer pixel shader effects, Personally I just got the original game and I think it looks pretty decent.
With the way systems are micromanaged, it takes very little cpu to calculate the ship encounters even in multiple regions(running AMD-64bit 3.4 Quadcore). I imagine A.I. and unit limitations are going to a trivial number imposed to conserve game length or no cap at all on units which I'd love to see. I've always played age of empires or starcraft and hated reaching that point of not being able to build more units.
The other point is the tech of the game will likely not be that of 2012 as you perceive it simply because the tech that they're building the game in mind with is today's technology or tomorrow's tech at best, personally I'd rather see them keep unit numbers way up if not much higher then the current cap and only a modest graphics improvement if that tradeoff must be made. Just my two cents but if the sequel does eat my current pcie2.0 card I'll just quad crossfire (only dual crossfire makes real sense, triple at most.)