Eh. He can say what he wants. He says the Gulf of Mexico is now the Gulf of America, he says Lake Ontario is now Lake America. Those changes reflect online for Americans, but for the rest of the world they keep their name.

Interesting question: if Trump declares Canada to be a state (ergo, the 51st) but has no military action behind it, and Ottawa doesn't declare it false, but instead seeks federal benefits for Canadians, what happens?

Game it out. So to the USA, Canada is a state. Candians now have American citizenship. Washington can ask Canadians for taxes, but they have no authority to enforce it. They can issue arrest warrants, but those can only be executed in the US. Any Canadian who does not travel to the US is safe. But if Canada is a state in the eyes of the US government, doesn't that just entitle Canadians to benefits? And doesn't Ottawa then get to send two senators and a certain number of representatives? Also, the Canadian embassy in the US closes because, to the US, Canada is part of the US. The ambassador in Canada also leaves because he or she believes Canada to be a state; therefore they have no job.

I say let Canada play it out, eh?