Correlation is not causation. And your mental model of how the cryptocurrency markets work is likely way too simplistic--did you know that cryptocurrency perpetual swap derivatives clear over $350B in daily volume?
Pretend for a moment that Tether pulls a Nixon, and closes the "dollar window" ending redeemability. Then what would be the difference between Tether and e.g. the BitMEX XBTUSD perpetual swap contract? Just think about it for a while.
You're missing the point: trading means that you have to find someone willing to do the trade with you. If no one wants to buy your Tethers then you're doomed. Redeeming is completely different - the issuer of your asset has a legal obligation to buy them from you (or at least that's how it should work for assets that aren't scam).
So why not short it against USD? The choice is there on Kraken, it's arguably the easiest win possible if you are convinced USDT will eventually go to zero in the next few years? It's certainly not going to shoot above $1.
Pretend for a moment that Tether pulls a Nixon, and closes the "dollar window" ending redeemability. Then what would be the difference between Tether and e.g. the BitMEX XBTUSD perpetual swap contract? Just think about it for a while.