No doubt ethereum is a very good technology but it will not replace bitcoin. There are other projects like Polkadot , Caradano or Binance smart chain which are strong cometitors for ethereum.
Also ethereum supply is not fixed but there will be some very good updates in eth 2.0 which will involve coin burn also.
We'll have to wait a few years to see that 2.0 update finish. I am with when the update is complete then ethereum supply in the market will be fixed and I think it will obviously improve eth coin for the better. Currently, the topic of discussion as an alternative to Ethereum which is experiencing transaction problems is the Binance chain.