The first computer cracking Bitcoiin will also crack your bank account, your credit cards, your online accounts, your messengers etc etc etc - and this wont happen any time soon.
Discussion
Wouldn't it theoretically be possible to fork bitcoin into a quantum resistant algorythm?
Anything is possible unless core thinks otherwise. then we'll fork without them and the longest chain wins.
The only problem I have with it is the stored static data that will be harvested and decrypted later.