Revive the old companies!

The other day I was sitting around, and I saw my old Sega Genesis. It was my second system, but really the first that got me into gaming. I had a Super Nintendo or a regular Nintendo, I can't remember which, before that, and the only game I can distinctly remember playing was Duck Hunt, with the orange light-gun! Anyway, I used to spend hours playing Sonic 1, 2, 3, Sonic and Knuckles with that cool extender pack, and a few other Sonic games. I had Road Rash, Golden Axe, Shinobi, Streets of Rage, Mortal Kombat, even a Pac-Man game! Those were good times! I was thinking, wouldn't it be cool if Sega got back into the console race? I would buy the system, and I'm sure everyone else would too! I remember playing Sonic Adventure for the first time on the Dreamcast at EB Games. I was thinking, "Wow, it is 3-D and I can move in all directions!" It was awesome! What other game companies or console makers who had given up due to loss of income or some other incident, should come back? What games do you think should have some sequels made for it? Post you thoughts in the comments!