This is very disappointing. The OA was an incredible, confusing, glorious piece of work, and Brit Marling, its co-creator, has assured us that it all has a plan and an ending.
Now (or back in August, anyway) she’s had to write its obituary. I suppose some other company might pick it up, but since it’s mostly Netflix who do that these days, it seems unlikely.
Presumably the two completed seasons, 16 episodes in total, will remain on Netflix. I‘d still recommend watching them. Just remember that you’ll be left somewhere strange.