There is a lot of things DL need to do.

For example... reopen a SkyClub at IAD. The Air France lounge does not count nor help. It is not smart for DL to not have a SC at IAD. Even if there are no DL international flights from IAD. Considering KLM, Air France, Alitalia* and Korean Air* are part of the SkyTeam and fly out of IAD.

I would think IAD is a major airport for the surrounding area of Washington D.C.

Who knows I might be flying on KLM from IAD to AMS and would be great to have a SC lounge at IAD.

*Alitalia and Korean Air : I am not sure if both airlines 'currently' fly out of IAD. Maybe they are seasonal flights?