I think the signs are clear that Martine Aubry will not be the next Prime Minister of France. After the election, there were indications out of Hollande's camp that, as a gesture of good will toward François Bayrou, who supported Hollande in round 2, the PS should withdraw its candidate against him in the legislative elections. Pierre Moscovici, Hollande's top lieutenant, made the point publicly and explicitly. But Martine Aubry, as party boss, had the final decision, and her answer was no. That is not a decision that Aubry would have taken, I think, were she on the verge of becoming PM.
As a matter of political tactics, one can argue the wisdom of the move either way. For it is an incontrovertible fact that any gesture of complicity with MoDem, no matter how insignificant, is viewed with suspicion by the left wing of the PS as well as the extreme left, with all its phobias about social treachery. And it's also true that MoDem voters did not come over to Hollande in large numbers, despite their leader's gesture of support. On the other hand, a party that assumes the presidency with a fairly weak mandate (a margin of just over 3%) might want to rassembler as a first priority. A symbolic nod to MoDem would cost little and might reap benefits later on.
Of course it is in Hollande's power to make more significant gestures, and it remains to be seen if he will do so. What is not a good sign is that Aubry is already marking her distance from the new president. If she persists in attempting to make herself the leader of the left wing of the PS by emphasizing her differences with Hollande, she will greatly complicate the already complicated situation of the new president. This minor skirmish may be forgotten in the months to come, or it may in retrospect loom as the first premonitory sign of the rock on which Hollande's presidency may founder. The endemic division of the Left has always been its Achilles' heel. Aubry might have waited a few days before reminding everyone that victory can exacerbate as well as heal old wounds.