What will happen? Not much. The network will agree on a different proof-of-work algorithm, one that quantum computing has little or no advantage in computing. Quantum computers are a lot less impressive than they've been made out to be, frankly. I mean like, a *lot* less impressive. Even when they're working, they won't be able to do anything regular computers can't. They'll just be able to solve *some* problems much faster. Not all, or even most.If you're buying the graphics card anyway, sure, pop another $50 into it or something just for mining I guess. For the fun of it and all. I wouldn't expect to make that $50 back though. FYI, ATI cards are much better for mining than NVIDIA. The two use different methods in their hardware implementation, and it just so happens that NVIDIA's method fucking sucks compared to ATI's for bitcoin mining. Just one of those coincidences.