Something for the A1200 which would combine the features of the Indivision, Graffiti and BlizzardVision would be ideal, in my mind.
Everything coming out of a single VGA/DVI/HDMI port of course. This would allow all existing software to be run (including the few RTG and 3D accelerated games that exist for the Classics) without the hassle of having a costly, hot, and hard to maintain BlizzardPPC+BVision combo.
I don't see any need to go significantly beyond the Permedia 2 performance level. Just something that combines all the good things, is easy to install and run, and robust.