2^64 is hardly horribly insecure. Its on the edge of what a gigantic compute cluster can do. So its not secure, but hardly horribly insecure. Especially even if you can get a quantum computter working, its not going to be on the same level of operations that a million dollars in AWS credits will get you. At least not for a very long time.

Besides,in most places where that is an issue, its trivial to switch to 256bit algorithms

> (CAVEAT: where the speedup is applicable, which is often hard.)

Grover's algorithm has pretty wide applicability. Its the exponential speed ups like shor's algorithm that have super limited applicability.