i hope never. you may want it out of good heart, but as a state, as a country - United States of America would only want this union in bad faith, just to use Russia as a temporary ally against China, as a source of cannon fodder to throw at China and with the scheme in mind that once China is defeated, Americans would strike Russia in the back and finish us off, assuring they are the only ones left on the planet with enough power for global domination
once Americans would destroy China and Russia - they would focus on India and make sure they never become super power and never challenge American hegemony
this is the only motivation for the American state for improving relations with Russia, there is no other thought. They don't care about our culture, our history or our people, we are just asset that for a time could be leveraged at a bigger threat to them - China.