I think all of them are clearly better than the four you listed. With or without a proper preparation. They wouldn't necessarily be MTFs. Chamrousse as used in the end of this design:
https://ridewithgps.com/routes/35931698
Chamrousse that way after Luitel and descending could be very good. But the last climb is long and fairly tough so it wouldn't be certain or even probably with attacks already on Luitel. It would definitely soften the riders legs, but I'm not sure it is a very high likelyhood of much action before the last climb to Camgrousse.
And that version of Loze is better than a pure MTF. Some descent and a short ramp at the end. Far better than for example an Alpe or Plateau de Beille finish. If ridden as hard as Jumbo and Pog did for the hardest three mountain stages this year, it is pretty likely that it would create big gaps. Bigger than a Iseran-Tignes finish would. The same applies for the Joux-Plane stage. If ridden hard earlier on the stage, the last climb to Joux-Plane and the descent to Morzine could create some big gaps.
The route next year is far from great, but it is still okay. I think I gave it a 6 (or 7?). But it is at least as good as many of the other routes the last decade or so.
And if we're talking about stages where climbs or combos of climbs are likely to create big gaps, I would think that most of the following covers the most of the best options in France:
Alps and Jura:
Iseran - Galibier - Granon. This is the one stage I would most like to see in the Tour. LDA could also be used, but Granon is just much tougher.
Bonette - Auron (preceeded by a couple of other climbs) like Allos-Cayolle or Izoard-Vars.
Loze - Vanoise or Meribel MTF.
Joux Plane to Morzine or Les Gets. Or Joux Plane - Joux Verte - Morzine. I would actually prefer the Les Gets finish if Joux Plane were preceeded by several other climbs.
Glandon/Croix de Fer - Madeleine - Valmorel, or even Chaussy - St.Francois Longchamps.
Mont du Chat - descent finish. Should of course be preceeded by other climbs.
Grand Colombier MTF (or descent finish) via Biche (and Lacets de Colombier)
Romme - Colombiere to Le Grand Bonard.
Pyrenees:
Aubisque - Spandelles - Hautacam.
Pailheres - Plateau de Bonascre
Portet MTF preceeded by some other climbs.
Pla d'Adet as used in 2005.
And you of course also have Ventoux which perhaps have the most brutal profile in France, and could be great if they were lucky with the weather (no headwind) and decided not to soft-pedal most of the climb.
The "holy grail" in the future:
Madeleide - Tougnete - Meribel or Vanoise MTF. Actually a quite possible stage in a couple of years from now.