I started off doing what I would like to see but in the end it devolved into the hopeless finish I can imagine ASO coming up with

For Grand Colombier it doesn't necessarily have to be an MTF (though that would seem likely) but instead could be a descent finish (I would hope for the hard steep side followed by a descent to Culoz, definitely not the MTF of 2020)
Izoard I just put in as a meme because I was annoyed they missed it this year, something more concrete is rumours of a stage from Manosque finishing at either Pra Loup or Super Sauze, with potential of a return to some big climbs in the southern alps. My only concern with trying to predict a stage like this is that with the 2024 Tour set to likely finish in Nice it would make more sense to highlight the southern alps in a big way that year, so I am really clueless with the main massifs.