I don't think that automatically follows. IAD is a challenging base to make work. Many have tried and given up, from Presidential Airways in the 1980s to at least one ULCC (F9?) more recently. Local O/D traffic dislikes IAD and connecting there can be difficult, especially if you are UX-to-UA or vice versa.

MWAA has a real incentive to play ball with UA if the latter articulates a serious drawdown plan.