Look at Zimbabwe, it could happen. The US government has no intention of stopping the printing presses, inflation will catch up to them eventually.
Yes. There is no guarantee that what happened to the Zimbabwean dollar can't happen to the US dollar as well. As you said, Ben Bernanke seems to be in a competition to print as many bills as possible. Soon we can expect something similar to this:
but when we predict the price of bitcoin we generally predict the price of bitcoin in relation to the current value of the dollar.
So when we say the price of bitcoin would in the future became $1.000.000 we mean that a single bitcoin would be approximatly buy you the same stuff you could buy with $1.000.000 today, even though by that time you'd need like $1.000.000.000.000.000.000.000 dollars to achieve the same due to inflation.
So a single bitcoin could become worth several trillions of dollars if you do not correct for inflation. But if you do correct for inflation than i'd say the maximum possible value would be about $10 million.