I think its now impossible to do so.But when quantum computing would be introduced after twenty years,then bitcoin's security might be compromised and bitcoin might get worthless.But we may expect that some precautions might be taken much before such disasters occur.
Think of new security measures. The world is changing rapidly and adapting to the new rules. So do not worry about security.
I do not know how much power I need to crack and so I can not say whether Bitcoin can be cracked with a quantum computer.