No, Hill 582 is in no danger from bulldozers. Geographically, picture a basic east-west axis. From north to south there is the SP (UP) Palmdale Cutoff, BNSF Mains 1 and 2, Hill 582, a bit of rugged landscape, BNSF Main 3, some more landscape, and then Highway 138.
As far as Amtrak No. 3 is concerned, I haven’t kept up with it for years. Even though I consider myself a Cajon Pass ‘local,’ I have no idea of No. 3’s current tendency, i.e., on time or late, passing before sunup or after it. If it is possible to see anything about the new construction, your seat would have to be at a left side window.
To hear you have had success in whipping cancer is good news. Cancers can be a mean villain. My sister-in-law died from it a few years ago down in the San Diego area. Of course, I suspected that as her eventuality. She was a chain smoker. Interestingly, she had just gotten remarried and finds out a few months later about her cancer. Her husband previously had buried a wife for cancer, and had to do it all over again with my sister-in-law! Sad story! So, it is good news that someone is having success in overcoming it, and it is hoped it stays that way for you!
As far as visiting Cajon Pass, you know your schedule better than I do. Personally, I consider the altering of Highway 138 in Cajon Pass historic. It would be most fascinating to see it before and after the alternation, and as a local I definitely plan on seeing it, and hope Caltrans doesn’t station guards on the hills with AK-47’s to keep lookie lous away, if you know what I mean.
Have a good trip,