Can ETH be used as a mainstream currency?

I spend ETH almost every day with my crypto card, it’s easy, but can it ever be used as a mainstream currency where merchants can accept ETH directly from the customer without the need of apps like Crypto.com and Plutus?

I know with the current GAS fee, ETH isn't very practical as a currency. Will the 2.0 upgrades make this possible for ERC20 tokens or is a layer 2 solution a better play?