Don't worry about Bitcoin, a small niche. The world will have BIGGER problems to worry about with the arrival of quantum computers. Hahaha.
The world will be able to fix the quantum issue and implement a quantum secure mode through rewinding, freezing, correcting accounts. But Bitcoin can't and that will lead to forks. We already have two main post quantum 'forks':
1. The original chain with all the coins. The 'shalecoins',
https://bitcointalksearch.org/topic/bitcoin-as-shalecoin-5134441 coins with no owner, will have new owners as it will be able to move these coins.
The original chain will remain the strongest chain. If some groups can reproduce the privatekeys of 'shalecoins',
coins with no owner https://bitcointalksearch.org/topic/bitcoin-as-shalecoin-5134441, it's their reward. They are trying to build a computer in the near future, that wouldn't be built so fast without that incentive. That opportunity accelerates the technology. If there are still some BTC owners
-incl. Satoshi- with old addresses and remove their coins now, they will be secure. So it's a fair game.
And nobody can change that game: Bitcoin rewards the best technology.The Bitcoin network is a pure competition network. Only the best technology will be successful here and make it secure. A Bitcoin fork without the old coins would be like another s**tcoin, because it would avoid real competition.
2. A fork without old coins which could be transferred by quantum computers.
(For example: Burn Satoshis coins to end the threat of prices crashing - Paxful Founder
https://bitcointalksearch.org/topic/burn-satoshis-coins-to-end-the-threat-of-prices-crashing-paxful-founder-5177563)
Both chains will be upgraded to quantum secure.
