I think the PS3 still has a lot left in it, at least for about a couple of more years. Sony probably wouldn't release a new system before 2014 anyway. And even after they do, the PS4 (or whatever they are going to call it) will end up costing more than a nuke, and I will wait at least an year or more before buying it, if decide to buy it.
As far as rumors go, pretty much everybody - including me - is unhappy about how PS4 is not backward compatible and how it will not allow used games to run. So I guess majority of the people will wait for some time for games to come out for the new console.