How long was the original going to be? There's only so much space in the plot of land it is on, guess they could have built a bigger mountain with more show scenes, that would have definitely extended the ride duration.
The log-bridge "concept art" was placed on construction walls while the ride is being constructed, (this year?) Presumably, at this point the construction plans are pretty much fixed, the purpose of said art is to advertise the project, not an Imagineering display in a blue sky cellar. Plus the art has a polish "attraction art" sheen to it, though it might be based on original concept art. Though I will admit that the log-bridge art was shown at D23 . . . so maybe, plans have changed, if so, then it doesn't seem right to use the stuff to advertise an attraction that they know won't have such a feature.
It would be like Toyota using concept art to advertise the Prius after production of the car was already in progress.