My guess for the plot "twist" based on the trailer
I'm not a smurf fan in general and I have no idea if the Lost Village is an already established story or something, but after watching the trailer I had a guess for how the story will go:
Smurfette is the only girl in a village of male Smurfs. She sees these ~mysterious stranger Smurfs~ and she goes on an adventure with some of her Smurf friends to try to find their secret village. Once they get there, they discover that the Mysterious Smurfs, who are all covered up originally, are all girl smurfs! Surprise! It's a village of Smurfettes. Bonus points if it's a village of all female Smurfs with one male Smurf, to mirror Smurfette's situation. Smurfette is tempted to stay with the all female Smurf village, but in the end (and probably after an attack from the evil wizard; maybe both villages have to team up to rescue Smurfs or take him down or something) they all live together! Happily ever after.