Well ETH may be the birthplace of the DE-FI craze but it won't be the only place that has it, I am pretty sure BNB chain, EOS and TRON will copy ETH as they always do and try to push down costs and grab users. I think that ETH 2 and shading will help make it cheaper but there's a limit to how cheap you can go without obliterating incentive to keep the network decentralised
I think that there's also side chains that will live ontop of ETH, I saw things like MATIC and I'm sure there will be ways to wrap ETH and BTC into side chains or other chains for more mircotrades and once you done move onto main chain and pay your on chain fee
This DE-FI craze has got a few rounds to go I am sure of it