Having been in this space for a while, I see a lot of parallels between the ICO wave today and the altcoin wave of 2014. The initial hype will give way to a more realistic view and many ICOs will realize their use case isn't working and will pivot -- many will fail.
2018 could be the year of . Interoperability is becoming more and more important and Interledger is still the only solution for interoperability beyond blockchain.
Interoperability will put pressure on special-purpose tokens. If I'm a file host for instance, my bills are servers and electricity and it'll be easier to pay them if I receive a more liquid token, so I have a strong incentive to accept one of the more mainstream cryptos, which I can more easily convert. And once users have a choice, they are more likely to pay with a more widely accepted token as well.
Finally, Bitcoin and Ethereum will continue to have stability issues and difficulties scaling, which presents opportunities for new challengers with real use cases and better tech.