I could see it happening. Mousasi is good but he hasn't fought anyone on Machida's level in how long? Hell, the last quality opponent he fought was King Mo and he lost. Next somewhat quality opponent he fought, it went to a draw. He hasn't impressed me in his fights with Latifi or OSP. Meanwhile, Machida stills looks as sharp as ever and has wins over top opponents and fought better competition than Mousasi.
Fedor = no reasonable argument for a claim at the GOAT title other than 10 years undefeated