We've seen full-length Muppets many times over the years, occasionally in
The Muppet Show and considerably more so in
The Muppet Movie and its sequels. So it's nothing new. Henson's goal with the Muppets from the start was to break free of the "proscenium arch" conventions of puppetry and create the illusion that Muppets were full-length creatures interacting in the real world with human beings, using only the television frame to conceal the performers, and often switching to marionette techniques to show the characters full-length. Sometimes he would experiment with other techniques like Japanese-style puppetry with black-suited performers invisible against a black background, or the more high-tech equivalent with bluescreens (this is how the birdlike creatures in
Labyrinth that could split apart their bodies were done). And Henson pioneered the use of CGI for character and set creation as well in
The Jim Henson Hour. He wasn't a purist about technique. He was willing to experiment with any technology that could help him create fantastic images, and loved to push the envelope and break free of conventional limits.
So if the Muppet characters in this movie are a mix of puppetry in standard setups and CGI for full-length or "stunt" shots, I think that would be entirely in the spirit of Henson's work.
I'm looking forward to watching this movie and hoping that it will be good, but I'm wary. With the exception of A Muppet Christmas Carol, there hasn't been a good Muppet movie since Jim Henson died. Not only that, but the additional loss of Richard Hunt has also hurt the Muppets, particularly Statler and Waldorf. I'm hoping for the best, but expecting the not so good.
Not to mention that Frank Oz rarely participates in the Muppets anymore; Eric Jacobson has taken over his characters. Jacobson does very good impressions of most of Oz's characters, much closer than Steve Whitmire's Kermit, but it's still not quite the same.
As far as the Muppet movies go, I'm actually pretty lukewarm about
The Great Muppet Caper and
The Muppets Take Manhattan, while I think the later films from
Christmas Carol through
Muppets from Space, and the 2002 Christmas TV movie, are actually fairly effective. It's their more recent stuff that I'm less sanguine about. The loss of the Muppets' head writer Jerry Juhl in 2005 was the greatest blow to the quality of the Muppet franchise. He was the head writer for most of the Muppet productions from
Sam and Friends all the way through
Muppets from Space (though he wasn't involved with
...Take Manhattan, or with the mediocre
Muppets Tonight TV revival). Aside from the 2002 Christmas movie (which was okay but not great), I've been rather unimpressed by the post-Juhl Muppet productions I've seen.