If I'm not mistaken, the netbook I'm writing on now has Intel GMA 950 graphics... and even though I tried, 0 A.D. were absolutely, utterly unplayable on it, with something that felt like 1-2 FPS per second. So I'd wager that on any computer without shader support the game will not be very pleasant anyway, and the people using such hardware will be fewer and fewer. 0 A.D. part 1 probably still has a couple years to go anyway, and throwing out some legacy cruft will at the very least not slow development down.