I haven’t seen it, but when the last book came out, knowing that it was going to become a movie, I wondered how they would make the characters look like teens. There was no way I could see.
Although computers can make Hobbits, I don’t think they can do the age regression thing convincing enough to portray the actors as high school seniors.
Still, the story needs to be finished.
Yes, and they couldn’t change actors. They just have to expect the fans to accept the situation for what it is. If they’d known how it would turn out all along, they could have shot seven films in seven years with the live cast, and then put in extra time on the special effects, spreading out the release over a longer period.