Like CAT, I'm mostly interested in £~200 cards.
I would argue that £300 is too expensive to be mainstream. The 970 was such a success partly because of how crap the 960 was.
But previously, cards like the 460 (<£200) have been the best-sellers. Also the 7850.
*IF* AMD can make a *cracking* £200 card, and not some super-gimped effort, then I could see it selling better than the £300 970, tbh.
Frankly I've talked myself out of buying some expensive, noisy, hot £300+ card. If I can't hear the clock ticking in the next room while I'm playing, or put my hand by the exhaust without getting 3rd degree burns, I'm not interested
The hot, noisy, power-hogging cards are dead to me

In that way I'm now possibly AMD's target demographic. Really pinning my hopes on a kick-ass £200 Polaris.
I'm sure AMD will deliver (I'll keep telling myself that until I really believe it!)