I'm not actually convinced that the Void will even get its own expansion. I expect everything surrounding it to be resolved during the MSQ's and side content.

Personally I would have liked the Thirteenth to be left broken if there's no opportunity for further Rejoinings to take place. The Voidsent have been a consistent threat looming in the background that the writers could draw upon as needed so if the Thirteenth ends up being 'saved' then that's one less potential threat and mystery to tap into.

The game has an unfortunate habit of going scorched earth with intriguing plot threads that could be left hanging to add a bit of depth to the overall story. Furthermore, unless a character is lucky enough to trend on Twitter than the writers don't seem to spend much time following up on them anyway.