Doesn't sound like anything has changed on his end, so why should it for you? I know how heart-wrenching it is to see dreams crumble and die. I'm sure you have pictures in your head of that bucket list item with both you and him in the front seat--and how sad it is that this will never happen.
I, too, feel that same heartache every time I see DGS. AH can't go with me because of the boundaries DS/DIL have set up. He says that not seeing his GS is tearing him apart, so what does he do? He emails the family that he has shaved his head, started on Antabuse, and is going to hit the gym so that he can have his old life back. When this text hit, I was on the road working and was thinking, what the heck???
When I got home, he had just gotten a haircut--not shaved his head; hadn't gone to the gym at all; and was drinking on top of the Antabuse. He admitted that he's trying to figure out how he can get around drinking and still take the Antabuse. So he still hasn't grabbed the golden ticket to his dream of having a life with DGS. And it sounds like your XAH hasn't exactly done anything other than write you a sappy email.
I know how you feel, but resist.