For our part, the consensus among the dev team is that the inclusion of live-action elements would actually detract from the realism of the game, not add to it - they would appear as flat planes in the 3D space, which would not be realistic at all. The only way around this would be a hybrid approach, like what was used in realMyst and End of Ages - CG characters with videos of actors as the textures.
However, the assets from the original game would not be suitable for that kind of usage, the performances would've had to be recorded with a special camera rig designed for that purpose. We would need to re-shoot them. This would mean getting a studio space, equipment, a crew...and actors. We would need to re-cast all of the roles, which would ultimately result in a new performance. By animating the characters by hand, we can capture exactly the original performance, comparing frame-by-frame if necessary.
This is one of the most contentious issues for the project, but we remain confident that we can deliver a high-quality, immersive experience with CG characters.