I don't get it. tether sucks. If you hold tether it may turn into air. But your bitcoin is still bitcoin. Also, when tether is going down wouldn't you want to sell it thus creating pressure in btc/tether market and value of of tether/btc going up? It's always been clear to me that USD/BTC and USDT/BTC are two different markets. USDT is just another cryptocurrency. Many of them were scams and disappeared and many more…
It will only create pressure on exchanges that allow you to actually sell USDT for BTC.
These will unfortunately be the same one that will likely go the MTGox route the quickest, leaving you a bag of virtual BTC that you can't withdraw.
Not your keys, not your coins, and doubly so for USDT.