Shale coins could still be a possibility but is it an issue? Thought gone coins coming back to circulation? Would it even be profitable to run a quantum machine for the length of time it takes on average to crack?
It will be at some point. It's also entirely possible for this to happen even before quantum computers are commercially available.
Because in the scenario where a quantum computer decode bitcoin transactions, then we will see a fork to recover the coins and an encryption upgrade, so, don't worry at all 
"Recovering" someone else's coins is a very slipper slope. What essentially happens is that you steal them in place of another thief.