I don't really see any altcoins take off unless they find their own niche or provide a killer app that really takes to the mainstream. It's going to be all about Bitcoin and Ethereum. Steem will do great because it is a killer app. It's stuff like Siacoin (hosting) or Syndicate (business) that may succeed.

That said, if you are trading, there's plenty of opportunity - coins will go up and down but mostly overall down. So time it right!