On the larger question of what the "new" Democratic party coalition will primarily focus on, I expect Teles is mostly right. Nancy Pelosi, Bob Casey, and the Blue Dog Democrats can all work together as a party if they focus on good government and bread and butter issues, and put the hot button cultural issues on the back burner. That is what will help keep their coalition together.
Put another way, the Democratic policy agenda will be shaped by the Democratic coalition, in no small part because the Democratic coalition will be preserved or destroyed by the choice of Democratic policy agendas.
Republicans, one assumes, already have anticipated this strategy. They will do their best to put cultural wedge issues involving sexuality and religion on the public agenda, as they successfully did before in the past twenty five years. Because they don't have to keep their coalition together to govern, this will be somewhat easier to do. The question is whether the Democrats can control the policy agenda and move it away from these hot button cultural issues. If they can't do this, then they won't be able to keep their majority.