On Crooked Timber, Henry Farrell has already emptied his glass of constitutional champagne and makes several quite reasonable predictions about the future of the formal and informal relations between the EP, the Commission, and the Council with respect to Commission appointments.
According to Henry, the EP will get a real, though informal, right to reject individual commissioners, a right that will later be recognized in possible treaty revisions. As a consequence, the Commission president will have a more powerful negotiating position with respect to choosing his team, which, in the end will lead to “a quite real increase in democratic legitimacy for the EU.”
I think this makes sense, although I’m not too sure about a formal recognition of “the right to choose”. I don’t think that will happen unless there are more – similarly important – de facto power shifts between EU institutions in the future.