How does Anthony Joshua keeps four belts?

[champion4ever]

Fight Pulev early 2020, have Usyk-Chisora happen at the same time, and then fight Usyk in the summer to settle the WBO, before making the WBA mandatory after that (Oquendo is still due, the fight likely doesn't do major business in the US or UK, so that'd be the type of fight you'd take to Nigeria with Joshua).

But once things are set, you're basically on the cycle for however long you'd be champion.

Joshua's title defense of his WBO title isn't due until June of 2020. That's approximately six months from now. Joshua's title defense of his IBF title is due in April of next year against Kubrat Pulev. He can defend both titles if he wants to because there are no unification or undisputed bouts on the horizon since both Wilder and Fury are off limits. They have a two way rematch clause in their contracts for their February 22 bout which is going to keep them busy for the balance of the year 2020.