Tether will almost certainly collapse, and then you'll have a lot of bitcoin chasing very few dollars. There is likely to be a stampede for dollars, which becomes a vicious cycle deflating the price of Bitcoin - the liquidity is consumed (Bitfinex is printing Tether because there aren't enough dollars to go around at unbanked exchanges, afterall) at the same time the downward volatility dramatically increases the perception of Bitcoin's risk; market makers start heading for the door; the cost of liquidity becomes massive.

There's some magic number for the price of Bitcoin, and it's hard to say what it is, where the miners start to lose money. If it stays too cheap for too long, it puts pressure on the miners to either switch to other coins or get out of the game entirely.

Things could get very bad, very quick. The only reason I don't have a bearish position in Bitcoin is that I can't find a counterparty that a.) I can afford at my account size (eg not CME) and b.) that I'm confident will still be around after this crash.

Stay cautious. Happy trading.