Exactly. So far, Ethereum is the most actively-developed smart contract platform in the world. Despite being slow and expensive at times, its large ecosystem of dApps and decentralized design, makes it the top choice among its competitors. Still, nothing lasts forever. If an Ethereum contender manages to become rock-solid in development and innovation, it might challenge ETH's place on the market. Most smart contract platforms have a greater level of centralization than Ethereum, making people think twice before choosing them on top of the original smart contract platform. I think Cardano is the only one that has a focus on decentralization just like Ethereum. It won't make use of DPoS for consensus, reducing the chances of becoming utterly centralized in the future (like it happened with both STEEM and TRON).

Cardano's innovative PoS algorithm could directly compete with the PoS version of Ethereum dubbed ETH 2.0. Charles Hoskinson worked with the Ethereum project before, so he has the necessary experience to make Cardano as good as Ethereum in the future. While I have to admit that development for ADA has been rather slow, it's has been doing great since its inception. This slow development phase could make Cardano secure and resilient unlike other competing smart contract platforms on the market. Neither EOS, TRON, or Tezos will be able to compete directly with Ethereum because of their utterly centralized structure. Which is why I strongly believe that Cardano is Ethereum's biggest contender in the crypto/Blockchain space. Unless another smart contract platform emerges with a focus on decentralization, Cardano will rise behind Ethereum in mainstream adoption and popularity in the not-so-distant future. Just my opinion