I believe a lot of wishes here may be a bit too unrealistic. You can forget about Plan Bois as it was tested in Dauphine and ended up with a protest day later. The Bagargi/Iraty finish if possible then not in 2023 as i believe the Tour in 2023 starts in Bilbao and after a most likely Jaizkibel stage to San Sebastian it will either teleport towards Dordogne or skimm the Pyrenees with a breakaway stage to Pau in 80's style with Bagargi, Soudet and Marie-Blanque before coming back to Haute-Pyrenees during the weekend. I think ASO tried to have a finish on Bagargi for either this or last year but apparently there were logistical problems with distances and lack of hotels. Apparently in 2015 La PSM just barely happened, only because of better connection with Pau. However, ASO also has a literal hard-on on Mende, which is in the middle of nowhere and has no problems with constant finishes there that will also repeat next year.
After the transfer to France the run-in to the Alps could include a bumpy stage on the Opale hills (like in 2012), a cobbled Paris-Roubaix alike and a quick transfer towards Dole (to commemorate Pasteur) and then enter Switzerland with a Dole - Lausanne stage. There's also a strong rumor connecting to Châtel (after Morgins?). It would be followed by a transitional stage to Chambéry/Aix-les-Bains and two heavy mountain stages to Granon (Madeleine-Galibier) and l'Alpe (Izoard-Lautaret-Sarenne?). Now, ther are apparently some problems here with ecologists (obviously) and sort of skimming through the Vars-Izoard 100th anniversary. Very early rumors had Barcelonette, higher focus on Southern Alps and possibly also having Alps as the last mountain block. Then it would work nicely with a Barcelonette (Gap?) - Granon stage after Vars and Izoard having a bigger role.
The transition towards the Pyrenees would go through a little village of Saint-Félicien (?) in Ardeche (most likely an uphill finish) and of course Mende because ASO treats this poor town like their favourite BMs to smack around for ish and giggles. Next stage should start in Rodez and go towards east Pyrenees (Carcassonne?).
The Spandelles is either reworked or has been to try for a Tour passage next year. Also Soudet north is smoothened out to have an easier descent. This would work with a Hautacam rumour for the last mountain stage, most likely after Aubisque and Spandelles. Other rumours include a Pailheres-Beile combo and a possibly 2013 Bigorre like stage with multiple cat. 1-2 climbs before the Hautacam stage. It would be followed up with a transitional stage towards Lot (possibly Cahors) and a hilly TT in/near Roccamadour.
I myself know that a non-MTF or easy-MTF last mountain stage is more attractive (this year's Vuelta and Giro being an obvious example) but ASO tends to not care about the race itself but only the revenue and a hard, flashy and well known HC MTF as the very last obstacle generates the most green. When they tried to be more progresive like in 2020 Roche-sur-Foron stage then sadly the race itself doesn't deliver, which definitely doesn't help. At least l'Alpe has a Sarenne variant so one day you may have a 100k (because marketing) Galibier-Sarenne-AdH stage as the last one.
BTW, yes, 95% of this info is from a certain well known site that host annual Tour rumours in French and i dunno if i can plug it in here.