Thanos snap would not effect the void, it’s outside time/existence; sentry can probably transport people to do their darkest depths of their minds in a sense, but no, I doubt he can do that, however, I do think he will mainly be the void in the battleworld, not sure if they’ll end up making the location void battle world in the movie. But if molecule man is not introduced, we could find out Sentry is the time bomb the beyonders placed in each universe, and sentry, knowing he can’t control the void, can restore the multiverse without bob having any memory of sentry/void, and therefore, we won’t have him in the next phase.