I really have no idea. If Arya basically gets a happy ending, rejoining her family and all, I do see her settling down with Gendry, why not? But if she gets more of a tragic ending, dying while or after killing whomever, then of course not. I really have no idea where GRRM is going with her story. The most common theory seems to be that sooner or later the Faceless Men will send Arya to kill someone and that's how she'll rejoin the other characters, but we'll see if that's what happens and if yes, how.