I'd agree that the future of cryptocurrencies which act as a store of value may rest in the hands of stablecoins, but that's not what Ethereum is: think of something like Amazon Web Services - a platform where you can build apps, businesses, and advanced software on top of. It's a company, not just some anonymous program intended to compete with the dollar like Bitcoin.

Also, stablecoins are usually built on top of decentralized apps which require the use of their proprietary coin (Ex: Ether or Binance tokens). Even if the future of cryptocurrencies is truly stablecoins, I'd argue that the platforms which function as a crux of the system represents a huge investment opportunity.