In 50 years time, why would a US, that has no interest in imported goods, does not need Arab oil, has divorced itself from any involvement in Europe, have any interest in maintaining an isolated outpost that cannot sustain itself, and which becomes ruinously expensive to maintain (ask the Dutch how expensive sea walls are). As for worrying about China, the US has basically surrendered the entire continent of Africa to China, through the withdrawal of its Soft Power (aka USAid). If America wants to replace all of its imported European cars with American cars, and all of its scotch with some sort of homebrew knockoff, why should it really care what Europe and China get up to? Maybe the EU can get in on the bidding war for the Chagos Islands, along with China and India, given that Trump has now formally acknowledged where sovereignty lies (Mauritius can only sell something it owns). The Louisiana Purchase and Alaska purchase were examples where it made economic sense for an expanding country to have these. The US Virgin Islands; purchased to stop Germany gaining a presence in the Caribbean, and affecting the Panama canal. Not really all that relevant now. Of course, how is the US going to pay for it. Its skint. There are cheaper ways to keep a presence in the Chagos. Be a better friend with the government of Mauritius than China might be a good start, stop pissing off the UK might be another.
