Why would they feel that need? If, hypothetically, they had a part which wiped the floor with G80 they could charge what they liked for it. It's not like the global economy has gone into meltdown in the last week and everyone is suddenly tightening their belts.
Agreed. Unless the price for R600 is completely out of whack (in which case I don't see how an extra couple of weeks can really help), they could release it (even at a premium price and in limited quantities), even if it's to get some mindshare. That would slow down G80 sales at the high end and even at the medium level. So I don't buy the PR line of "we chose not to compete in order to compete better later".
Something is definitely very wrong, I think.
Which probably means that the performance/$ is worse then for the G80.
If they have the absolute best performance, they can release their part, and promise lower priced parts for later.