My sad conclusion is that nothing will wind up being done to repair the Palisades. An historically accurate repair would require stone masons used to using BIG rock, and there are very few of those type left. One that I knew decades ago did work for my parents. Part of his resumé was doing the restoration on Cliff Palace at Mesa Verde, but he passed away a number of years ago. The cost of the restoration would be very high, even if someone qualified could be found to do it.
Sadly, the US Forest Service has had its mission perverted by the politicians from maintaining the natural and historical heritage of the National Forests to a "mission" of protecting private trophy homes built on private property in stupid places where they are vulnerable to wildfires. Meanwhile, there is a very strong and vocal minority both inside and outside of the Forest Service that essentially hates any roads on the public lands. The de facto result of that is that roads which deteriorate or are damaged beyond a certain point simply are not repaired and are closed. That list, especially here in the Rocky Mountain West, gets longer every year.
I used to live in Gunnison and I know the Alpine Tunnel area very well. The Palisades really are/were an engineering marvel, but even such marvels can't always stand up to the whims of nature. I'm glad that I got to see the Palisades while they were intact. There are a whole lot of other pieces of Colorado history that I got to see before they were gone. I'm thankful that I got to see those, too.