Puntland is not a secessionist state. It is formally part of the federal government of Somalia, unlike Somaliland, which has declared secession since 1991.
The challenge with Puntland is that it has the ability to exercise veto power over developments it doesn't like by threatening to pull out of the government—not to be secessionist, but simply pull out of the government. In terms of bringing them on board, I think there's going to be a different answer for the two.
For Puntland, it's going to be the same process that's going to gradually bring all of the other federal member states into a more coherent union. That is a federal system that is going to take time.
Right now it is a mediated state in which central government has limited leverage over at least some of the federal member states. If the federal government has a strategy in which it uses incentives to draw in these states, to provide benefits to them, as opposed to simply trying to manipulate them and undermine them—which has been the impulse lately on the part of Mogadishu— they could create an environment in which these states see it in their interest to gradually integrate more into a Somalia, whether federal or unitary.