They're going to have to start over with a whole new cast of characters, mainly of the young and pretty type. Tho I would not be at all adverse to seeing actors like Nana Visitor or Jeffrey Combs again, most likely not reprising old roles.
on cable (someplace respectable, eg, not SyFy) could be a prestigious enough name to attract some fairly big name actors. Folks like Kevin Bacon and Dustin Hoffman are making TV now. Let's get Meryl Streep to play an insane Starfleet admiral!