Thats the things, there's going to be a failure, somewhere with something. Crypto's fail every week, just none of the big ones yet.
I would almost put money on Bitconnect disappearing very rapidly. It just screams scam.
Tether I think will stay around, people don't hold it to gain value, it should be seen as low risk. I like it as its cheaper and quicker to trade with than BTC, and its cleaner on my spreadsheets in terms of fiat value.