Ethereum as a currency will never go mainstream with a price swings like this
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/
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.