Good point all, Cola. The first thing I thought when I heard about this was that it was yet another way for the Dine to mess with the Hopi.
As successful as some of the Dine casinos might be lately, I have a hard time believing the tribe has ~1 billion to finance this. Or anything close. Paving the road kicks things up a notch, to say nothing of a gondola down to the river level. If the Hualapai somehow managed to pave the road to the skywalk, they'd have a lot more visitors. We should also remember that in the 70s the Havasupai had to emphatically turn down government offers to build a road down into the canyon. I'm sure there's still disagreement amongst the tribe as to the wisdom of that, but opening the Pandora's Box of having motorized transit down from the rim (mules and raft guiding are bad enough) is a scary thought.