Even IF Ethereum falls more in its price, it will not mean that this is the end of this cryptocurrency. The market capitalization of ETH is great, and it seems to me, it is even growing now. Simply do not worry.
I also think that until the end of ETH there is still a lot of time since new tokens are created on this platform every day. If there is no Ethereum, then many altcoins will cease to exist as well. Even if Vitaly Buterin leaves, other people will be engaged in the promotion.