that they have some really great ideas that need to be tested (or many of which may already have been tested), but in the works none the less, and that they have a lot of talented minds working toward getting it right, questioning everything that we're questioning in this forum & more, and will continue making tweeks until they get it just right.
I think PJ has worked for quite some time now with many people on ideas of how this would work best, including when Del Toro was more involved and they were all sharing these ideas, and had the top minds from WETA involved...I have faith that they'll get it right. Whether it's animatronics or CGI or a combo of both, and whether the lips move or not, and how that fits with the actor's voice or not, will all have to be worked out.
I can't recall...did Treebeard have moving lips or just a mouth?