There are more twists left in this plot

As Fraser said earlier, the rebellion has not been defeated: Brown has not had some moment that restores his authority. Instead, he has made the same pledges that he has made before—to set out his vision, to be more inclusive and to call off his bully boys—and they look like they will be enough to buy him a few more weeks.

But these pledges won’t be met because Brown can’t change. (Hands up if anyone thinks we’ll make it through the summer without a minister being briefed against by Downing Street). So, soon enough there will be another trigger for a rebellion—defeat in Norwich North or a string of polls with Labour in the teens, say—and the whole show will start all over again. 

The longer that this goes on, the more damage will be inflicted on the Labour party. Brown can’t restore his authority, so logically Labour should get rid of him.