Frontier definately wants to add more flights to DCA and LGA but slots aren't available (at least at a decent price).

The DOT ruled Republic was not a limited incumbent carrier at LGA or DCA and therefore isn't eligible to purchase/bid on any slots that might become available if Delta/U.S. Airways go ahead with the slot swap. Republic has a large portfolio of slots at DCA and LGA that they purchased a few years back and now lease to U.S. Airways.

Unless circumstances change significantly, the best Frontier can hope for is securing another slot or two to beef-up the MKE, MCI, or DEN routes.