Why does everybody say this is a stupid question? The only reason I would avoid making a thread with this topic is because it attracks lots of bullshit posts.
If the PS3 is an utter and complete failure, than yes, Sony might be looking into a new name for their next console. Sony has lots of advertising power, so I have no doubt they could make a new brand name take off.
Some people say the Nintendo analogy is not appropriate, but I don't see exactly why. For the casuals it was the gameboy, not the Nintendo gameboy. Just last week I heard a friend say "Nintendo, is that also from Sony?". Just to illustrate that the connection between Brand name and Platform isn't that big. And with the Wii Nintendo's trying to avoid the brand name alltogether anyway.
What is the big difference between Nintendo and Sony, is that Nintendo has a few franchises that attract people, no matter what system they are on. Pokemon and Mario to name a few. The connection Pokémon-Nintendo isn't made by the costumers, but the pokémon games do bring people to the new Nintendo platform. Sony has quite a few franchises, but I belief they wouldn't suffice to guide people to a Sony platform with a new name. At least not the casual gamers (maybe Buzz and Singstar could in the PAL region, but then again: they are just a quiz and karaoke game. If Nintendo comes with their own version of Buzz and Singstar, it could be over for these games). So as I said earlier: the marketing machine of Sony would have to be in overdrive. It would take lots of effort and money to set the new brand name in the market, but it could pay off massive, while staying with the Playstation name could be a burden.