Sorry but it sounds false to me.
Bar BB all currents Younko are weaker than PrimeBeard by a good margin, they can't be equal to Roger
You really think two of BM, BB and Kaido will help Luffy after he beat them ? They aren't Crocodile or others Villains.
Law and Killer are rival to Luffy they won't either.
I think you contradict yourself you think Roger can win against each elder high diff and each one Zoro, Law, Kid and so on will won Extrême High diff
So how are they stronger ?
I think it will be Shanks and Big Mom in specifics
Dragon may replace Big Mom though...
However Out of everyone I mentioned, I feel Dragon is gonna die... yes I believe Shanks will stay alive till the end but Dragon will not
I think there is too much emphasis by Oda to call Sabo "next generation leader of Rev Army"
As if it's coming... the time for Sabo to lead them
As for Shanks, I believe he's gonna be defeated by BB, BUT ultimately survive death, kinda like Marco now