I have never said would be, since the future is uncertain. I have said should be. There are no other country in the world more active in spreading democracy than US, including military affairs.
The USA has been the high water mark in known History imo and has mostly been a good steward of Western Civilization's virtues and also done well exporting them culturally over it's centuries...hopefully that will continue for some time yet...
But just as on the personal scale wise Monarchs must concern themselves with a strong succession to maintain the gains they have made for their people, on the state scale wise Empires must concern themselves with a strong succession to maintain the gains they have made for their Civilization.
Western Civilization has been adept at keeping the 'torch' lit by passing it on. America has had its day [which is not yet over] but its night will come and then like Greece passing the torch to Rome it will have to pass the torch to another to carry Western Civilization on beyond 'the fall of the American Empire' just as Britain passed the torch to it...imo India is the most likely successor...if it is properly prepared to pick up the torch when the time comes.
The Future falling to China is not a Fate worthy of contemplating :-(.