I think most cyclists will probably stay in the road on that steep downhill. Depending on how tight the turn is onto Joyce St., cyclists could continue to ride on Joyce St. going south. They could maintain enough speed to ride somewhat comfortably with traffic. Otherwise, they could slow down and get onto the southbound sidewalk on Joyce St.
In a few years, the situation could be complicated by streetcar tracks, if that ever gets funded and built. The streetcar is supposed to head down Columbia Pike and onto Joyce St., on the way to Pentagon City and Crystal City. There are already some issues with cyclists and the new streetcar tracks in NE DC. If it’s too dangerous to zoom down that hill with the tracks in the road, then most cyclists might ride on an expanded sidewalk on Columbia Pike down to Joyce St. I don’t know if there are plans to add a more substantial bike trail on the side of that section of Columbia Pike. There’s certainly room for one. The area is currently a parking lot so they can set aside as much room as necessary for a decent bike path and sidewalk.