Followup to my most recent post. I've found the weasel words buried in the WMATA's SafeTrack plan (pdf) regarding all "extended hours", including late-night service on weekends: "Will reevaluate once system is in state of good repair".
Those are not the words of a transit operator committed to restoring late-night services.
You might get late-night Metrorail service back someday. But my guess is that you'll probably have to fight for it.