This has already been discussed in the history of this thread. Certainly, quantum computing could recover these lost coins again some day. But this technology will also be the end of Bitcoin (unless it will not be equiped with better quantum computing resistant algorithms before) and thus the recovered Bitcoins are completely worthless.
Answer : NONE
You just have to wait for a Quantum computer that can calculate the private keys.
I know it is a tricky question. What do you think, how many Bitcoins are lost forever and are 'out of the network' by lost private keys?
Answer : NONE
You just have to wait for a Quantum computer that can calculate the private keys.