Plenty of nations in Europe and North America have language minorities, to a greater or lesser degree. Even generally culturally homogenous countries like Sweden have small ethnolinguistic minorities that, again, to a greater or lesser degree, enjoy some kind of legal protections to help support their continued existence. But while we have a few examples of nations like Belgium, where the desire for linguistic rights has led to two vigorously self-sustaining language communities within one country, or Luxembourg, which has a really wild example of polyglossia, it's (understandably) not very common to have two or more major language communities in a Western country that are more or less on equal footing. So under what kind of circumstances might we see larger nations—say, the size of France (66 million) or Germany (80 million) that have two (or more) major, largely equal language communities?
Bonus points if the two languages are not a Germanic and a Romance language. Double bonus points if the outcome does not involve a large territorial change (like, say, Napoleonic France swallowing Italy/Germany/etc. whole).
Note that the situation of Austria-Hungary is not really what I'm looking for—there was a cornucopia of languages within the Empire, to be sure, but it was clear who was top dog among them. "Fringe cases" might be places like Canada, where French is dominant in Québec, to be sure, but which, with only 20% francophones vs. 65% anglophones, borders on being a very large minority language. (Edited to add: Switzerland likely fits in as another fringe case, with German at 65%, French at 22%, and Italian at 8%, but again, the goal is to see how large a country like this can get.)