The thing is, Canadian provinces have long lacked the impetus to actually try and work together on anything, especially the economy, because the US is a giant crutch. And the country has consistently worked to worsen the rights of Canadians in the name of gaining access to US markets.
This all hurts both countries. But walking away from an abusive relationship hurts, too.
It sounds like community pruning is the better solution here. Users don't need to find dead remote communities in their search results. If there are multiple active communities, that's not an issue, and there's no real reason to homogenize them behind lizard brain FOMO. If there's one active community and 6 dead ones, there's no reason for users to find any of the dead ones.
Forcibly merging communities that exist on completely different websites just because they run the same, or even just similar, software continues to scream "I want centralization".