All conceptual given that UA and AA will have to pick up the cost for the majority of this, and in addition landing fees/rent charges will go up for all carriers.
One thing to note, T5 has to be done first before anything else starts. By adding on 9 gates, it opens up moving non UA/AA carriers to T5 from within the domestic core. How many non UA/AA carriers are there?
Also, this ties into the busing operation mentioned in another thread, the current checkpoint could not handle the amount of passengers being forecast.