bitcoin will never be able to suck all the fiat money, they can just print more without problem
also fiat is already worthless, but you're obligated to use it for the majority of things
if you mean collapsed, i don't think so
Problem here is because world was sold centuries ago..
Now those owners won't let you to takeover. Money will stay as their way of enslaving people.
And if dollar collapse this is just because they let him go..
people can decide what money they want to use, if they decide to use bitcoin, fiat will collapse for sure, government can not obligate the usage of money, but they can put deterrent to rpevent people from using other kind of money, by "banning it"