> Could Dexter be made with Netflix / streaming as it's only distribution model?

I don't see why not, once execs are comfortable with it. Of course, it would still air on broadcast TV, which won't go away entirely, and you'd have to run promotional/marketing materials to make people aware of its presence on the streaming sites (the sites themselves would probably do a lot of that for free, since they benefit too).

There's no inherent reason this can't pull in at least as much money as the current model.