Yet again, this guy (OP) is a pretty big manic with ideas that come out of his ass. I don't understand why people think the US dollar is going to fall, and crypto is just going to swoop in and take over.
This may sound unreal at first, but if we add some history to the mix it starts to acquire shape.
All fiat currencies tend to hyperinflate and die at some point and their average lifespan is less than 50 years. The oldest existing currency is the British Pound, if i'm not mistaken.
Most countries in the world had several currencies already, so yes, USD could die and will almost certainly die at some point. The transition can be painless, like the introduction of the Euro in the EU, or not so much, like the fall of VEF, ZWD, and many others. Will Bitcoin take over? I don't think so, but it will serve as an alternative for people scared of another great depression.
If USD falls, everything falls. You're talking about a currency that everyone uses around the world, and if the US has issues with banking / stock market then the rest of the world has issues as well.
Crypto will die if USD dies.
Banks worldwide use it, normal people don't. I live in the EU and I travel quite a lot, but I've never been to the US and I remember one time, about 8 years ago, that I held a dollar bill. It was the second time in my life.
Crypto will take a huge hit if USD dies, but it won't die, just like gold won't die when a fiat currency dies. There's a fiat currency dying somewhere right now and the commodity and crypto markets remain unaffected.