Quantum Computers will exists alongside traditional computers, they won't be fast enough in all applications for it to make sense getting rid of traditional computing, so AMD doesn't have much to be worried about.
Their most likely practical use cases will be as accelerator "add-ins" (very large ones) to traditional supercomputers for the first couple of decades. If they can ever scale the cooling challenges and such down enough to be viable for consumers, it will be as an acceleration unit type thing, no one is going to abandon a century of software.