Where does this fear come from? I've seen a few people say it, but as the flagship show, I feel like they'll attempt five seasons if it kills them.This is why I find this particular forum so fascinating - what actually is the Future of Trek now? I'm not sure any of us have a clue. Only a couple of years ago, "nuTrek" was going great guns - it felt like we'd have a constant stream of new content. I'd have said Captain Seven was a shoe-in. It felt they were going for all-year-round ST. Now it feels really different. Is Academy and the half hour comedy really it with the occasional movie thrown in?
My guess is what happens next depends totally on how S31 performs - because that movie is the test of whether or not the one-off format performs well enough. If it performs - expect more movies with different one-off stories and/or sequels (I suspect Legacy might be a shoe-in for that). If it doesn't - thats that door closed.
My personal view is that SNW is going to end with S4. I just have this nasty feeling about it. My personal take would be that Legacy or similar should replace it - essentially something that takes the post TNG era forward. The TOS-ish era is done to death, but the 25th century has so much potential and the TNG era is where so much of the fanbase started it feels like more should be done with it.
I say "flagship" as its the only word I can use to describe it with. Neither SFA or Newsome's comedy can quite fit the bill, if you know what I mean.