There should be a lot available for purchase when released, but it might be a good idea to wait for non-reference coolers. AMD is not having the fab issues Nvidia is having right now with their TSMC 16nm FinFET process. It's so bad that Nvidia can't manufacture any 1060s to compete with the RX 480 so AMD will have the mid-range market to themselves. I would think Nvidia would need to discount 980s drastically to have anything to compete for the foreseable future.
I am seriously interested in upgrading from my 7850 but it would have to partial fund the upgrade I just don't know how much I would get for my 7850 2GB it's fully boxed and what not and very clean hardly no dust etc I was thinking possible £90 I'm the original owner from when it was launched about 5-6 years ago I think it was. My only gripe would be my motherboard it's a PCI-E x16 2.0 slot and that would lower what I would get from the RX480, and thus it would mean a complete CPU/Motherboard upgrade on top which could be partial funded I suppose but it's a lot of messing around.