Brook should fight a couple of fights at this level and hope Khan does the same and they can both have their big domestic fight.
Maybe not internationally, but at home yeah. Hell, they could stage Hatton vs. Witter now and despite being well over a decade too late (and dragging both off their fat retired arses) you know it would sell out Wembley. Brits love them a bitter, long-simmering domestic feud.
No way would it sell out Wembley, for a rivalry to sell it has to be built up and made when everyone is interested. They could do 02 arena but nothing over 30,000
Mind, it was Hatton vs. Witter that I said would sell out Wembley even in 2018 (and I do believe it would), not Khan vs. Brook...
I wouldn't put him on GGG's level at this point but he is definitely on par or above Spence. I personally think that he is a better boxer and brings more power to the table than Spence. Brook's skills are not in question but his ability to take punishment is because he will receive numerous power shots in vulnerable places. I don't think that he will function at his best when he starts to feel the pain in familiar places and his brain plays back the consequences of those shots.
154 seems to be his division. He was bound to move up and went all the way to 160 anyways for GGG. I just think he needs to settle in this division though. Sadam Ali comes to mind.