I'm not so secretly hoping that next year's Crisis on Infinite Earths crossover stays true to it's comic origins and she goes out then.
I've been thinking that they are gonna use Crisis to put Supergirl on the same Earth as the rest of the Arrowverse. She was only on another Earth because it started on a different channel.
This was my original theory as well. But hearing about how many of the shows are flagging in ratings, and Supergirl is, IIRC, the most expensive special effects budget, she might be on the chopping block and it would make a comic appropriate send off.
Then worse to worse the Monitor tucks her into the pocket universe (I believe in the original Superboy Prime ended up there) in case she's needed later.
Lol i would bang her and Melissa Bemoist.Caity Lotz as Supergirl? Never knew that I always wanted it.
This next season looks fucking crazy lol.