The logical way to end it (for now at least) is to have him faced with the unwanted truth that he himself has become The Void. Or Is in real danger of crossing the line into that territory.
I think myself when Osborn recently reinforced the idea in his mind that there was no Void and it was all inside his head it became a self fullfilling prophesy as The Void finally had the power of self-belief to flip over and start taking over Sentry fully. That's why he's increasingly become more loyal to Osborn and may be a part explanation as to who Osborns mysterious Ally/Weapon is - what is The Void is so dominant it is not only now able to seperate from Sentry but has control over him as well?
I think that's the sort of direction they're headed in and has been foreshadowed for much of Bendis' time with the character, that Sentry/Void are one and the same and Bob's going to have to face up to what's going on in his head and what he's responsible for because of his own weakness. It may even be that the reason he's gotten more powerful is due to this mental reinforcing reinforcing of Osborns, with none of the friction between him denying the Void he has better access to his full power range...
(Alternatly wouldn't it be wild if he was revealed to be (at least partly) Odin? Mad idea sure but remember Marnot?
Sentry could be some sort of contingency plan of Odins to get him out of jail at the right time).
It would fit with a lot of Odin's past behavior, such as the Marnot incident or creating a human persona for Thor to be grafted to in the form of Dr. Blake. Didn't Odin also once walk the earth as a homeless man under self-imposed amnesia?
And it also would make his "higher than top tier" rep palatable if he's really a Skyfather.
Of course, I don't think any of the speculation about Sentry turning out to be some other established character will turn out to be the case, unless Paul Jenkins no longer has any say in the matter. I doubt it's what he intended for the character and he seems pretty protective of his golden boy. But if your Odin theory panned out, I'd be all for it.