The devs are so badass, they constantly mention that they will allow miners to accept any currency for gas fees if it is feasible. Most of us who have some Ether are comfortable with this move too, ironically our hedge for this scenario is to hold some Bitcoin.
Because, Ethereum will prosper not when Ether has a high market cap, only if it can become robust enough to provide a decentralized platform to run code for a variety of apps and services.