Weaker fundamentals? Do you really think the relationships with third world countries are more strained than were during active colonization? Russia and China did a lot of work with their infrastructure programs but I am still not sure they have the upper hand.
Our industrial base is gutted and we don't have enough resources. Not enough to sustain our extravagant lifestyles.
Europe has to find a way to buy Rubles quickly or choose between freezing or damaging capital goods (there are industries that cant be shut down because they get damaged).
There’s not enough American LNG to rescue Europe, and if there were there arent enough ports to import it. Anyway, nascent American populism will make sure Americans get (cheap) gas first.