Unlike bitcoin which was originally intended to be used by the consumer for paying for real-world things, ETH is mostly intended to be used for paying for 'gas' in order to execute code in the virtual machine. The good thing is that gas and ETH have been decoupled, which means that the gas prices are always constant, and what you pay per transaction tends to get automatically adjusted based on the price of Ether, so transaction costs don't fluctuate as much.
What you're probably interested in are "Stable Coins", crypto that is pegged to a fiat currency such as the USD or EUR. It may be possible that stable coins may be developed to run on top of Ethereum as smart contracts. One interesting project under development is Maker Dao, see https://makerdao.com/
No crypto-currency will be mainstream because payment verification takes longer. Credit cards can now confirm a payment in less than a second with contactless payments.
Where those technologies will rather be used is in the background. Storing those payments or access to details across companies could be done more efficiently than currently.
