Ethereum is getting a revamp and will launch version 2.0. If this version is not good then another project will emerge and everyone will leave Ethereum.
Exactly. Market capitalization is nothing, as it only reflects the value of an specific cryptocurrency's circulating supply. What matters here is usability and mainstream adoption above anything else. Both Tether and Ethereum are different from the other because of the way they were designed. Saying that Tether will replace Ethereum is like saying Fiat (USD, Euro, etc.) will replace crypto. Fiat will always dominate the market because it's the unit of account in the mainstream economy. This means that Tether's USDT stablecoin might come on top (in terms of market cap) within the not-so-distant future. But Ethereum will remain in the lead of the smart contracts space regardless of its current position on the market. We might as well focus on each cryptocurrencies' use cases, instead of figuring out which will overcome the other.
All in all, Ethereum has nothing to lose since Tether relies on Ethereum to succeed. After all, people need ETH to process USDT transactions. The more USDT grows in usage, the more adoption ETH will experience in the mainstream world. It's a win-win situation for both crypto assets. With ETH 2.0 coming soon, Tether will be able to enjoy faster transaction confirmation times at a fraction of the cost. Just my thoughts