IGN: Do we see Lexa in the finale or is this it for her for now?

Rothenberg: We do not see Lexa in the finale. I’m not sure that that’s a tremendous spoiler. Her story, essentially, is over. She made her choice and she’s not turning her back on that choice. She’s not going to have some sort of second thoughts and come racing back into the fray. That’s just not the way we do things. But she’s alive and she’s out there and you better believe I am already working on AMC to allow us to keep working with her because I love the character and I really do think that Alycia has been everything I wanted in that character. Negotiations are ongoing.

IGN: Negotiations are ongoing! Her story’s over this season, but there is hope for future storylines is what you’re saying?

Rothenberg: Yeah, Lexa is still in command on the ground. There will definitely be, I think as a result of what happened, huge, huge storyline ramifications going forward. Had we killed her, that would have been way less interesting. There’s so much more we can play with with her now. There are secrets out there. How is Clarke going to respond?

http://uk.ign.com/articles/2015/03/09/the-100-creator-on-lexas-big-choice-and-cl arkes-next-move-in-the-season-finale?page=2