SATA3 6Gbps is not going to have a long life span where SSDs are concerned, that is for sure. SandForce SF-2000 family of SSD controllers will max that out Q1 2011.
IMO what is needed is a dedicated high speed SSD interface. OCZ have HSDL, and use it on their IBIS series of SSDs.
Should there be a SATA4 standard, doubling the speed form SATA3 is not going to be enough. SATA needs to be moved from the slow speed south bridge/PCH to the high speed north bridge.
I have never heard of a single failure of NAND memory on an OCZ SSD, there have been a few controller failures (Indilinx), and a fair number of early SandForce based drives getting stuck in a panic mode due to a firmware bug (I believe). Those drives needed a factory reflash, but from what I understand, these drives have NOT actually died, although that may have been the way the customer perceived the problem.