Do people realize that, in order for Cross Guild to be considered a "Yonko level threat" we kinda needed both Big Mom and Kaido out of the picture?
The SH's+grand fleet and the Cross Guild are simply the next biggest threats.
Take a step back from "mihawk and croco are buggy's bitches" and "mihawk solos yonko+yonko crew", take a deep breath, and think for a second about the current state of the world.
Despite Buggy being a fodder, his group was strong enough for the WG to offer him the position of Warlord. Croc merely got the "appeared too soon in shounen" treatment. He's like Freaza. Lost to a Super Sayan 1, only to come back with a single PU and start being on the level of Super Sayan God Blue Ur Mom Goku. Croco getting this kind of "buff" to be relevant at this stage of power creep is absolutely feasible.
If not Cross Guild, then who would be the next biggest threat? Kidd and his Crew? Law and his crew? Being REALLY generous and saying both Kidd and Law would be on pair with Mihawk, and Killer would be on pair with Crocodile, the rest of their crews suck ass compared to Buggy's and probably what Crocodile might have gathered in the New World.
Having said that: