It would probably look like this:
I love 2D games and I love HD....Just the idea of mixing the two makes me moist. (Ask Joe Burling)
I think Sega should take cue from Capcom's: Super Street fighter II Turbo HD Remix (except for the ridiculously long title) and recreate an original Sonic game in High Definition. It would sell a metric shit ton...Heck I'll even bet Sonic would sell 1 million copies the first day.
Here's to hoping my wet-dream becomes a reality...Now if only Microsoft would fix their horrible iteration of a D-pad, the world would be a better place.
Artist Credit: AlchemistDefined