Obviously Ethereum is one of the top project in blockchain industry now.Most of the ico are based on ethereum smart contract.
Highly qualified developer work with ethereum and most importantly vitalik is behind this project.So you can invest without any concern.
Ethereum will last a long time, because ethereum is still used and periodically, ethereum smart contracts continue to increase in demand. Altcoins should also be like this, in case of the product, it is needed and used by the public. If not so, quickly slow, their platform will lose value and of course the price.