The US has 50 states with 310+ million people. Mexico has 120+ million, sooooo...the appropriate number of states is probably in the teens. So let’s say 16. Some states are combined and others left alone. Admitting all 31 plus Mexico City may be a tough sell, but Mexico would fight a single-digit number tooth and nail. Based on population figures, 16 seems like the best number.
PR may or may not be admitted, but if Mexico City is admitted, DC almost has to be. So 67 right off. 68 if we go with PR. That seems fair.
And if we add Canada...lot of pissed off Canucks right off. And Quebec may secede and not go along with it. So let’s see here...Ontario gets in by itself. Maaaybe they merge Manitoba and Saskatchewan. All the Maritimes merge. So 5 or 6 states. Let’s say 6 for the powerful Western Canada lobby. So 74 now. Maybe add Guam/American Samoa/the Pacific territories into one state for 75.
There are a lot of common sense mergers - for example, Coahuila, Nuevo Leon and Tamaulipas merge rather nicely into the State of Rio Grande.
The issue with allowing too many Mexican states is that - in addition to more votes in the Senate - is that a good chunk of them are pretty small population wise. Only 14 of them have more than 3 million people - for comparison, 35 US states do.
I can see Mexico reduced to a dozen states as a compromise. 12 is a good number.
As for Canada, I see the only issue being the Maritimes... no freaking way do we give Prince Edward Island 2 Senators. Merge them into one Acadian state. Hell, maybe toss Newfoundland in there too.
That makes 7 Canadian states and 12 Mexican states. The United States of America with 69 states, make ya jokes now. Plus, Puerto Rico still dragging its feet from making an even 70.
As far as language, compromise - federal education funding will go towards two languages per state, one of which must always be English. French can still be taught in Quebec, Spanish in Mexico, and lots of room everywhere else to get creative.