We wont be sealing Primals, that simply wouldn't make sense with the upcoming planned content. While Free Company Primal summoning hasn't been a topic talked about by YoshiP a lot, the last time it was brought up he said they were waiting for it to make sense within the context of the story. If we seal them, it would only make sense if that seal fails almost instantly...

I find it more likely that "The Rejoining" mentioned in 2.4 as the subject matter behind the Isle of Val incident could likely change the rules on Primals and allow them to exist without draining the planet of Aether. Meaning they stop being such a major threat and allows us to summon them.