"If we're fortunate, and the audience appreciates the movie, we're already writing a sequel screenplay, and some other Smurfs will come forward, who are already in this movie. There are about 10 that you only see in passing, like Vanity, and others who will come forward in the second movie."
Clearly Vanity is the priority
And it's been announced they've already completed the screenplay.
So that means more Vanity content for me and for all who love him so... he may be one of the main characters. I have seen the video of this interview countless times. The way Jordan Kerner puts his hand to the side, and says "Like Vanityyy..." in a special voice with a smile, than goes back to say "and others who will come forward" in his regular tone... tells us Vanity is unique and lovable and will have a very strong presence in the second film.