Beterbiev seems to be a different kind of specimen where he's still fighting like as if he's in his prime as he gets older. Of course it's more ideal that he's younger and fresher but I don't think it'll look any more different whatever age he is against Bivol regardless of the results this Saturday. That's assuming Beterbiev is just as sharp as he was against Callum Smith. I'll say this, I don't think anyone would have given Bivol any chance at all 4 years back. The Canelo fight really helped put Bivol on the map and show everyone just how good he is. Technically speaking were it not for Canelo jumping in we might have seen Bivol facing Beterbiev sooner, but at the same time perhaps most people wouldn't think too much about Bivol. Honestly I believe Canelo helped make this fight feel even more important. Bivol beating Canelo really elevated his status as an elite fighter. It's why I think this fight is even bigger now more than ever. Hopefully Beterbiev's age doesn't play a huge factor in the end result of the fight.
It is bigger than it ever would have been now, for exactly the reasons you state. Bivol schooled Canelo and Beterbiev still knocks out everyone who looks at him the wrong way. However it is still prime Vs past prime, undoubtedly. Prime Beterbiev wrecks him.