Actually everything up to Punk Hazard has at least been dubbed. We know they started work on Dressrosa. So the hard part will be casting characters from Zou onward.
Looking at the Wiki, they'd need to cast Katakuri, Carrot, Reiju, Ichiji, Niji, Yonji, Big Mom's three helpers (all share the same voice), Kaido, Smoothie, Cracker, Pica, Jack, Perospero, Momonosuke, Judge, Pudding, and Brulee. ... Yeah that's a lot of new characters to cast. I know it will be for the anime too but damn.
Saint Seiya did get a new dub for Netflix so they could use that. Also, the whole "different studio" isn't just Yu-Gi-Oh related. You have dubs produced by Funimation in Texas, but also dubs produced by Viz and Aniplex in California. Also, Death Note's dub was Canadian so that's another mess.
It's on Punk Hazard, where have you been?