The Spanish region of Catalonia has held two referenda on independence, one in 2014 and another in 2017. The latter caused a constitutional crisis in which Catalan leaders were arrested and the region was placed under "direct rule" for six months.
Will Catalonia hold another referendum on independence before the end of the decade?
Separatism is caused by the government. In Quebec French is taught as an appendage to english- you're supposed to use English and French is a luxury. Once the government collapses the real language will win. Ethnic separatism is a luxury that exists when times are good, not a natural state.
These ethnic identities are a few decades old. In Quebec it's obviously new. In Europe they didn't have education for that long and anthropologists created the languages in the 19th century to be taught in school. So once those schools go away, since capitalism is collapsing in 2026, all that will go.
There's not any real examples of this happening but consider in existing failed states, like Somalia or Afghanistan the cia failed to create ethnic rivalry and instead relies on political or religious movements, and religion is dying too.