True, but the point is the NES and SNES were cartidges, but they were the same kinds. When Sony started with the discs, it became easier to think that the tech would support the old and the new. But I wonder if Sony is doing this so that PS3 will continue to sell. You'd imagine that most people would just forget about the PS3 once they upgrade, even though the PS2 seemed to somehow survive for a long time.
But looking at some of the things Sony is saying, it almost seems like they are trying to "reboot" things, and starting off completely fresh with this console. I saw this video on IGN where they made an interesting point, where Sony showed some of their first party franchises, but they didn't number them. They didn't say Killzone 4 or inFamous 3. It's almost like they're not trying to continue what started on PS3, but rather starting off something fresh based on old ideas, which is the opposite of what Nintendo has fallen into with their franchises, where every Zelda or Mario game follows a similar trend.