The two generation rule is a bit of a myth.
Nintendo has won with the following:
Game & Watch to Game Boy to Game Boy Advance to DS
Thats 4 in a row, 40m to 118m to 83m to 84.55m (and counting)
Its more like...two generations is the most you can go without innovating to draw in a new audience.
So NES-SNES were the same audience.
PS1-PS2 were the same audience.
Neither was particularly different in terms of innovation, the latter just had better and more diverse versions of earlier games.
DS would have failed as a souped up GBA because Sony would have won over the GBA demographic in the way it had won most of the SNES/Genesis demographic with PS1. DS still probably lost about 20m or 30m gamers to PSP but it drew in enough new ones (as PSP has done too) that its not exactly hurting Nintendo's bottom line.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu
