Doolittle will close and Madson will set up is my guess. It sounds like Kelley and Glover will be maybe a few weeks off from the Expanded Roster date, so they may just hold them on th DL and set up rehab assignments to coincide with that timeframe.
I have a feeling that the Nats may decide to swing for another relief arm or get a starter since Ross is now out and Roark is out and Fedde is likely not ready. I think EJax will be a fill in until the deadline. It looks like Gio is on his way to his 12 Million dollar vesting option for 2018 (180 innings pitched this season) but my guess would be that Fedde could be dealt for a starter so the Nats have someone under control for a few more years to go with Scherzer, Strasburg, Gio, and hopefully Roark and once Gio is gone, Ross or Fedde is ready for that 5th spot.