The idea of doing both films and tv seasons at the same time was how they were planning to do The Dark Tower. The idea was to do one film, then a season, then another film and so on, with the same cast and everything. I'm not sure if that's still the plan though. It's an interesting idea but would probably be hard to do without confusing chunks of the audience.
I'm guessing a Dune tv series would probably just be a spin off set in that world.