It is a weird situation. It is clear that Anatoly has been doing some work with him in recent fights as his movement and style has definitely adapted recently and it would be more of Anatoly's philosophy. However he's obviously pre-occupied with his son and considering Lomachenko is most likely a permanent fixture in the States, Usyk will have to join them if he wants to be trained by Anatoly and even then Anatoly might not want to give time to training Usyk full time even though he's probably like a second son to him. Usyk seems like a home bird though so I am not sure if that will come to fruition anyway. He can pick and choose his trainers though, who wouldn't want to work with a once in a generation talent like Usyk.
Switching partners can only help accumulate knowledge, most humans are ears deep in emotions...so they end up developing strong emotional bonds with the trainer... The CMD feeding USYK brain, keeps spitting out "I feel", "I feel" to comfort the emotional peasants