I doubt that they would announce it's the final season, but there's a chance it could be. They'll probably look at the numbers in the second half of the season and decide then. However, I wonder about the Batwoman thing. This could be some kind of combo of what they did with Legends of Tomorrow and Flash--seeding in characters on the other shows and giving them a back door pilot.
A pilot for what? Maybe Birds of Prey or maybe Batwoman. They have Black Canary and a few other birds--with Batwoman that gives them an anchor for a new TV show. One that could either be added to the others, or replace one of the others.
Unfortunately, this means that if they canned ARROW, Felcitiy could still continue as Oracle on a Birds of Prey type of series. Every silver lining has a cloud.