Fringe is the only one that's even somewhat surprising, as far as renewal at all. Believe it or not, Community's terrible ratings still put it at about the network's average scripted show ratings (for just the Spring, anyways). NBC is just doing that terribly.
(warning, incoming rant)
The strategy that seems to be developing from them is interesting. And by interesting, I mean stupid. This past fall, they only started 2 new sitcoms (Whitney and Up All Night), and put all there eggs in one basket by advertising the hell out of them (especially Whitney as I recall). Which sort of worked, for a little while. But then the novelty wore off, and coupled with them all but neglecting advertising their veteran shows, everything tanked to new lows that NBC has still not recovered from. The only thing that didn't tank interestingly was Community, because it started at its low point as everything toppled around it (but not before the hiatus announcement).
Fast forward to this Spring, and they've been doing the opposite. They signed new shows that they've barely advertised while no longer completely neglecting their veteran shows. And then thanks to Community's hiatus, and possibly because NBC seems too afraid of how bad re-run ratings will dip for them, they have to do some odd schedule shuffleboard to fit everything. And what happens here? The new shows tank right out of the gate, doing worse than both the vets and the fall rookies.
So what are they prepped to do for next Fall? The same thing they did this Spring, but on crack. They've signed so many shows that they can't seriously expect to advertise all of them that thoroughly, and seeing what sticks regardless. I expect a lot of early season cancellations from them.
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"One toot on this whistle will take you to a far away land."
-Toad, SMB3