Year 1600, your ship sinks with a chest full of gold Year 2000 someone builds a submarine and recovers it Year 2012 you lose a hard drive with 1000 BTC on it Year 2040 someone builds a quantum computer and recovers it Should the saying "finders keepers" apply?
Holding the keys is 10 / 10ths of the law with Bitcoin. The test is: 1) Can you move it around on chain? 2) Did you get that ability without subverting another person’s same ability? If yes to both, then enjoy it.
absolutely yes
commies will hate this
By the time it's feasible to do so, I think everyone actively using Bitcoin (I.e. hasn't lost their keys) will have moved any significant sum to some sort of novel quantum-difficult wallet. Realistically, there may also be some sort of regulation (or at least convention) beyond simple finders-keepers by then.