I don't think so since defi project are just new in the crypto market and many people are not familiar with it while ethereum is already built its name and credibility that is why a lot of people are trusting it, in fact most of the newly established project now are eth based token so replacing eth is quite far to happen.
Do you realize that Ethereum is a blockchain that being use by DeFi project as platform for there product? They are not competitors but rather partners. So there is no way that ETH will overtake by DeFi project. Project that can overtake ETH are those Blockchain-based project too that can cater DeFi project like Tron, BSC, EOS and many more.
You should DYOR as well as the OP.