i didnt even think there were that many Son'a to begin with, considering the Son'a are just Ba'ku outcasts and the ba'ku population wasnt that massive itself since they could all have fit into one federation holoship. especially since most the son'a leadership died in Insurrection?
I think the Son'a would be more likely to join the Klingons than the Feds. And the Ba'ku, assuming they still have the same philosophy as they did in Insurrection, would stay in isolation in the Briar Patch. They don't even have ships.
the son'a? theres like 5 of them left, the rest were mercenaries. Join isn't the word lol.