The acceptance is most important thing in cryptocurrency as a payment system. People will stack only those assets that they can trade to another. For example you use cash because you know that the owner of your favorite coffee shop will accept it as a payment, he knows that his providers will also do, and so on. Crypto was created by people to people. P2P. Without third parties. So I think it will always be accepted, even if it will not gain giddy success
Of course ICOs will be forgotten. Without acceptance of the industry everything will be forgotten. But in my opinion this will not happen in nearest future, I see cryptocurrencies as the perfect cash system among others existing