From what i have been reading, a rough calculation seems that the new 40terraflops would be able to hit 1GHZ per card. That would indeed be interesting time for miners but then again .. we are heading for POS soon so it wont effect much.
I think you missed a decimal place. A card with 1024GB/s of memory bandwidth would have a theoretical limit of 128Mh/s since ethash requires 8MB of random memory reads. In practical terms, that would mean an actual hashrate of ~100Mh/s.