Americas 51st and 52nd States?

[ag]

Puerto Rico - possible, may be even probable. Cuba - not before Mexico and Canada do the same. It's not an extension of Florida, believe it or not, Castro or no Castro. 

[ag]

With Cuba I'm talking about maybe 30-40 years after the death of Castro and the fall of his regime. Sorry about not stating that before.

Not even then.  The chance that Cuba would enter, at this point, is no higher than that for any other neighboring country.  Why Cuba and not, say, Panama? At least, there are anglophone areas (though small) in that country.

Except for Puerto Rico, none of the countries in the region are at all likely.  Guam +, of course, could be another possibility w/ somewhat larger population.

[ag]

as Puerto Rico is equal to MA

Puerto Rico is not "equal" to MA. At present, there are no Rep or Dem organizations in the country, so any prediction is difficult, since the local party system would change after statehood.  However, at present there are two major parties of similar strength on the island, and it is not unlikely that one of them would become the basis for the local Republican Party organization (given that one of the two parties is already affiliated to national Dems, this becomes even more likely).  Now, this might be a very peculiar Republican organization, dissident within the national party on many issues, but it would still be a Republican Party, and it would be a locally important force. A moderate and/or Hispanic Republican candidate would have a good chance of winning PR in a presidential election.  I don't believe MA could be, at present, competitive, given almost any realistic Republican candidate.