I like your optimism, but he's fighting a guy who is much, much bigger than the guys he went to decision with in the past, and a guy who seemingly doesn't slow down at all.
If DDP were halfway likely to slow down in R3 or R4 to any meaningful extent, I might agree with you.
As it is, I think DDP gives Chimaev all he can handle early, and it just becomes a slog for Khamzat thereafter.
I still expect Khamzat to probably take R1, but not easily, and I just think he's outmatched athletically.
This narrative about Dricus having endless cardio and never getting tired is becoming a bit overstated.
It's also based mostly on fights where he had the takedown threat in his favor.
He gassed and lost round 2 vs Till, is one example. Then finished him in round 3.
He looked gassed and sloppy vs Brunson after a lot of grappling. Finished him later in round 2.
He lost round 3 to Izzy, huffing and puffing after failing takedowns, he lost round 5 to Strickland. Finished Izzy in round 4, went to decisions with Strickland.
I think both of them have a very good ability to keep fighting and stay effective even while they are tired.
They might have a round or a minute or so where they look spent, but they then catch a second and third wind.
They don't look to pace themselves for a decision, they both aim to get their opponent out of there.
I much prefer this style of fighting compared to fighters who are scared to invest the energy needed to finish the fight.
Athletically, I think both of them are very strong but I would definitely give the speed and agility advantage to Khamzat, and I could see that coming into play in the wrestling/grappling exchanges.