I don't think that it will be able to replace it for so many reasons. But let's just set back with the actuality of the stand of these two projects on their consistency on this market and its own communities. It is more obvious that Ethereum has produced a lot of smart contracts and successful projects that have been so good and got their own mainnets.
The Ethereum ecosystem is more widely used than Cardano, in fact there are several more advantages to using Ethereum.
Exactly. If it's just about the ecosystem of Ethereum entirely, it's a no match for Cardano. While there are pros and cons pertaining to each others competition but it's just more with the Ethereum ecosystem thats being liked by most of the people not just as an investment but also with its utility that everybody does.
I don't think Cardano will replace ethereum, I have tried transactions on Cardano several times, and it is very difficult and the fees are expensive, for this type of cheap coin the fees should not be expensive.
So I don't think Cardano can replace Ethereum based on my experience exploring the ecosystem of these two coins.
It is far from replacing it and there have been always topics like this about replacing one and the other. This has also been dealt with Bitcoin and for that reason, it's not going to happen but since this market is volatile it may not be Cardano but there could be another one.