I dont think it will be a "hard tank" but I dont see this team being competitive for a couple more seasons. Nats dont have much in the way of committments, but they don't have a lot of talent projected to take over the MLB roster. None of the top 5 prospects are going to be MLB ready until next season, and thats assuming great development and no injuries.
I really dont see Rutledge, Cavalli, or Antuna being MLB ready until 2023. Probably about the time Garcia is ready as well. By that point, I assume Strasburg and Corbin will be albatrosses. I dont see Scherzer being a top of the rotation guy in his age 39 season.