I'm not sure about forever staying but what i believe is Ethereum is here for us to make profit as long as we trusted this and as long as we wanted too.
ETH had been proven to be climbing with bitcoin for how many years now and also known to be an altcoin king.
so investing in this coin assures you income in long term as what bitcoin can do.
i would say yes, Ethereum will survive cause i believe they always trying to be better. I do also believe ETH will be use by many enterprise as a public blockchain, we already see so many cases in supply chain that can help enterprise to reduce cost and it will be adopted by many enterprise, and currently i think the best blockchain for it is ETH.
Lol really Staying Forever?

though ethereum team is keeping the progress for this coin but of course forever is too much to mention .