The Nats actually have some experience with this. They buried John Lannan in AAA in 2012 after he had a good ERA year in 2011 and four straight decent back-end MLB seasons (nowhere near as good at pitching as Roark though). He demanded a trade, Nats never obliged, and they ended up non-tendering him after 2012.
Considering they have Blake Treinen, Taylor Jordan, and AJ Cole (also Joe Ross in AA/AAA), I wonder if they'll take the different road and just trade Roark right now.
Alternatively, make him a long reliever I guess. Fister, Stras aren't exactly pictures of health. People have long doubted Scherzer's mechanics. Gio throws a lot of breaking balls (less lately).