Read up on Bernal's pace on the Col de l'Iseran on that stage. It is almost beyond comprehension, especially at that altitude and late in the 3rd week. His "ceiling" is enormous. I have absolutely zero doubt whatsoever that Bernal would have increased his winning margin had that stage not been shortened. All the facts say JA was more likely to lose more time had that stage not been shortened. Bernal isn't a bad descender either so JA would not have forged a big enough gap to stave off what would have happened on the climb to Tignes.
Well that's just it. We don't know 100% for sure that he could have kept that pace up, solo, on the 20km long, 1000m vertical mountain, ahead of a strong chasing group, on gradients that would give an advantage to riders in a group, on a cold day. We don't even know for sure if the plan wasn't for G to bridge up to him, and that maybe Ineos didn't even plan for him to be able to maintain that effort all the way to the end.
If he would have got to the finish with a 5.00 lead a la Ben O'Connor, then it would have been one of the all-time great rides. If he'd blown up with 5km to go and been at a standstill as the MJ group rolled by, then it would have been just like Kruiswijk on the Alpe the year before. The truth is probably somewhere in the middle, (and there's a lot of middle there) but we'll never know.
I just hope at next year's Tour we see a full-fitness Bernal, vs a full-fitness Pogacar, with a few others like Vingegaard, Almeida, Roglic et al thrown in. And obviously the dream is for Pinot to beat them all.