Since there are so many pie-in-the-sky suggestions in this thread, I'll make one of my own:

I'm sure PIT would be willing to lease gate space out cheaply--Lord knows they have enough of it. Buy a bunch more Q400s, turn PIT into a QX superhub serving a couple dozen east coast destinations, and connect PIT with SEA with hourly frequencies.

Since the all-F Q400s are so much more comfortable than the competitors' RJs with only a few seats of F, and since the aircraft only "sip" fuel and thus can sustain lower fares, it's simply a given that everyone will flock to the newly-rebranded Alaska East Airlines (operated by Horizon) featuring industry-leading East Of Expected™ service and the award-winning Mileage Plan, thus turning it into the most successful carrier in the nation.