Look at Dogecoin. The market cap of Doge is now bigger than Litecoin (the forked coin) . We don't want to join the POS experiment, so we simply move to a more stable, secure and advanced technology POW. By forking, we can remove the whole management of the coin, the devs and the assets of their supporters.
Then we can push the coin in the right direction.
At launch all Ethereum holders that haven't locked their funds for staking will receive the same amount of ethereum as they own. Currently this number is 89,2% of the supply but this it is expected to decrease if more users join the ethereum 2.0 staking pool.
So the 11.8% who have locked their funds in Ethereum 2.0, will loose their coins in the new Ethereum.