Question: Are Violet and Mike stuck as being blue and stretched out permanently?
Answer: In the original movie with Gene Wilder, Wonka assures Charlie that "they will be returned to their nasty selves." In this version they are stuck like that forever as a lesson to other children.
Answer: It's unknown if they'll stay that way for the rest of their lives or if they'll eventually return to normal.
Answer: Yes.
Answer: It's left vague in the film, but in the book, it's made clear that yes, they are stuck that way.