Cardano may surpass ETH, but not to destroy it.
They can move together and work together.
Especially on this time of bloody market. it is not good to beat other but try to hold hands and make good improvement.
If Cardano wants to have more value and ETH to surpass the fall, they should do a partnership.
Yes. Cardano would perform a lot better if it makes a partnership with Ethereum. After all, Cardano's founder (Charles Hoskinson) worked on Ethereum previously, so it wouldn't hurt to make alliances with the Ethereum development team to help make the ecosystem better. AFAIK, Cardano has a solid development team with a good long-term vision to make the platform as secure and scalable as possible. Right now, ADA is in its very beginnings since it's only been nearly a year since its inception.
There's a lot of work to be done, as Cardano becomes a fully developed smart contract platform with greater transaction throughput and cheaper fees than Ethereum itself. While I believe that Ethereum will always be the winner, Cardano could be seen as the second alternative to Ethereum due to its robustness and highly secure environment for smart contract development. IMO, Cardano looks even better and more decentralized than EOS, which means that it has all the possibilities to become a serious competitor against Ethereum. However, it cannot destroy ETH due to its years of establishment in the blockchain space, and brand recognition. Just like Bitcoin is still the leader of cryptocurrencies (despite the fact that many other alternatives had emerged), Ethereum will be the same while Cardano stays behind it for many years to come. Just my opinion