Its similar to Intel's move to DDR2, not really much performance gain (some), but paves the way for more improvements. Its really a reverse of what happened already, intel->LGA775+DDR2=weak gains, AMD brings out 64-bit, kicks ass. Just reverse the cycle and repeat. However, I don't think AMD will be nearly as slow to make the next step as intel was (its still not happened yet btw).
But I hardly think AMD will have no chips available on the release date, its too big of a sign of weakness to do that right now. They'll be there, and plenty of them, don't worry about that. The release is a month and a half away and we've seen working boards from multiple companies and chips too.