Again, they spent their whole time talking about Mantle at the Hawaii launch? Firstly, it wasn't a Hawaii launch, they launched a few cards and announced Hawaii but it most certainly wasn't a launch. Secondly, for a 1-2 hour thing, they mentioned Mantle, in passing, at the very end of the conference for about 2 minutes. So utter rubbish in "spending the whole time talking about Mantle". They barely said anything at all about Mantle and a relative launch of the rebranded 7000 series cards where they also announced the 290x was coming soon basically.
As for DX12... frankly the thing that worries me most is how close it is. If MS have decided on a new direction for DX12 and to actually make a good API and they've decided on this direction in the past 2-3 months, I'm exceptionally worried if it comes out any time soon.
Hopefully launch of DX12 won't be any time remotely soon and they actually mean it when they say they want to improve it to be a great API. Of course, MS has said as much and attempted to fix the driver overhead MANY times in the past, in DX10, 11, 11.1 and 11.2 there are all things that are supposed to drastically improve it and most dev's find most of the fixes barely do anything.