I don't see the benefit of just re-mastering some of the episodes -- that might be enough to put on home video, but it wouldn't be enough to widely syndicate. If CBS is going to make the investment of getting a team together to re-scan the negatives and build CGI assets, that's an awfully big investment to make on such a limited prospect as a "Best of" DVD or Blu-Ray.
But as an advance? i.e., they put out DVD/Blu-Ray of, say, BotW/Family and Unification (5 episodes, one - Family - practically a "bottle show" for effects). They then plough that money back into the major remastering effort, with several major assets - the Ent-D model, Borg Cube model, Warbird and some others - now effectively paid for, and some major stock shots fully rendered.