I wouldn’t say ‘doomed’, but yes.
I believe that God will find a way to allow a set of political arrangements to thrive that promote His morality. A culture that understands this can lead, or at least follow. A culture that, as a whole, consciously rejects Biblical morality will not last more than a few generations.
And when America inevitably falls, will it have a purifying effect? In other words, will America, or what remains of it, be a better country after a collapse? And if the answer is yes, then shouldn’t we actually welcome the collapse in a certain sense?
Sorry, but where in the Bible does it say that things are going to get better?