It's absurdly premature to even consider where Usyk ranks on any all-time P4P list. Moroever, I still rate Usyk behind Holyfield on the cruiser GOAT list. Nevertheless I think he'd be one hell of a handful for "Real Deal."
The problem with this is that after 154 years of Queensbury rules, there have been so many unique fighters with unique accomplishments. I prefer to say that he is a first-tier ATG and leave it at that.