There have been rumors for a while that Intel will introduce a multi-core x86-compliant CPU where some of the cores (depending on need) can be used as a GPU.
Considering Intel's GPU history, I wouldn't bet on it. But if this does happen and is at least comparable with on-die AMD+ATI, I think the direction of CPU development will be set for many years: gazillion multi-purpose cores. That doesn't mean that a PlayStation won't have a custom built CPU, but the likelihood of it is small considering the shrinking life cycle of the consoles.
Diogen.