I wonder if they could develop a concept like the BBC's Playhouse, where potential pilots were shown as single episodes. The one with the highest ratings could then become a new series.
A series about the crew of a newer ship, like the Aventine
and Captain Ezri Dax, would be good, and so would a series about Klingon and/or Cardassian mercenaries, I think.
books have good adventures, but some of its more-exotic crewmembers might be difficult to depict on the small screen.)