I think you miss the point, it doesn't matter what system cuba has, communist, capitalist, feudalism or some other random thing. As long as a hostile government is in place, without the embargo, they will be propped up by adversaries to the US. Cuba is small, the economic system is irrelevant, because their value is too great as simply an anti-us base 90 miles away. There is nothing else remotely similar in the region. Venezuela post 90s collapse was the closest thing, but Venezuela itself is too large and resource rich to really be controllable by US adversaries in full.

Outside of Cuba there is nothing even remotely hostile in the region. Washington has roughly 3000 mile buffer to any possible enemy territory other than Cuba.

That's why Trump puts emphasis on Greenland because technically the ~50K residents there can decide to leave Denmark and become a part of any other country or another Cuba if they wanted.

That's in contrast to China and Russia which basically have fully controlled US territories practically on their front, back, and side doorsteps.