The writers obviously left her story open ended so that they could bring her back if they wanted to. The writing was very strong in the last episode and I think that this may be the final season because it seems like the story is being wrapped up character development wise. However, with the story of Derek and Jesse comes a tragic ending.
I think the only way we will ever see Jesse again is if the fans of the show make a big enough uproar about the exit of her character that the writers sieze the opportunity to bring her back in as another female badass. Though probably not this season, seeing as how we already have Sarah, Cameron, and Weaver. The only problem I see with the Jesse coming back Scenario is that we won't ever get to see Chola again gawddammit! Seriously, the writers need to bring that girl back as a T-808e5208357209hi whatever model they want. It's the only way to solidify the badassness of this show's female cast. Lord knows John Connor is the only gay man in my life right now that I feel the strong urge to slap.
So get out there and make an upheavil about Jesse's unfortunate end. I mean what the hell Derek!? just fucking kill yourself you asshole. gawd, i'm not straight but I'll take her off your hands if that's what you need.