has already gone longer than 7 seasons with cast changes - and location and time changes.
TV is undergoing big structural changes so that the logic that drove the need for one hour episodes minus ads every week for 22 or 25 weeks out of the year is breaking down.
Netflix is releasing a bunch of new Arrested Development
episodes at the same time. In the future, the notion of seasons will become moot. The question will be, how many episodes do you need to tell your story?
American Horror Story
's anthology format that might also be a good model for future Star Trek
series. Seven seasons with the same location and cast seems too long, but keep evolving and there's no reason it ever needs to end.