Re: What will happen if quantum computer owners start to move the early mined coins?
Technology is rapidly evolving in our age, and it won't take too long before this Quantum Computers will take over the blockchain and destroys it, that is why we are hoping they won't get that far because we are doomed once that happens, and when that time comes, I bet you would take back these words that you have said, and rephrase it to something more wary about quantum computers in the future. 
All people who say that quantum computers won't exist: who will give them back their Bitcoins if they don't improve the network and don't transfer to quantum computer resistant addresses?
Quantum computers will exist.
There's a lot of time to update Bitcoin to an even stronger encryption.
We will have a quantum resistant upgrade. People will transfer their coins to quantum resistant addresses, but a lot of coins (million+) won't be moved to these secure addresses as they are "lost" coins and nobody can move them.
Which fork will you use post quantum?
a) the fork with all Bitcoins where quantum computer owners will get the "lost" coins and will be the new owners.
b) the fork where "lost" coins are burnt and can't have new owners.