Full POS will only affect ETH Ethereum. Ethereum Classic ETC is making more money than ETH right now and will be POW for a good many years yet no plans to go POS. There is also ETG Ethereum Genesys which has already successfully forked so they should come onboard as well. As for EIP 1559 yes the gas fees will be reduced but this will be offset by a price increase, so net shouldn't be an issue.