We can't be too sure about this till the fight happens only then can we find out if Joseph parker can beat Usyk or not. Am a big supporter of Usyk, but I also understand that Usyk cannot be champion forever. At some point he's going to lose unless he retire before then. Joseph parker has been winning his recent matches same as Usyk so you can't completely write off Parker. Parker is also showing some similarities that Usyk was showing back then when he was rising to stardom. Usyk Vs Parker would have been more interesting than what we saw against Dubios.
Maybe you're right, as I said, I am not familiar with Parker, so I don't know the full scope of his boxing skills. He might give Usyk more of a challenge than Dubois did, but I still don't think he'll beat Usyk.
Anyway, we'll see what happens in their fight, they still have almost a month to get to an agreement.