If the gas price is not reduce after starting ETH 2.0. People will seek for another blockchain. This cause the user of ether will decrease. One day ether will lose their user.
Ethereum is a pretty good blockchain project and as far as I know it will be pretty hard for the users as well as the organizations to move their smart contract to any other blockchain and with such secure code. So I think even if the fees isn't reduced after the ETH 2.0 goes live on mainnet then too the people will stick to it, although it will be sad for me also to see the high transaction fees in the ETH 2.0 as well, I used to arbitrage the coins on the Dexes but with the high transaction fees involved in these transactions it has become pretty hard to do so.