Well Khan has probably caught him at the best time in terms of Brook having taking a couple.of beatings and having both his eye sockets fractured so there's more vulnerability to him as a fighter. Problem is Khan has also became more vulnerable, brutally KOd v Canelo and hurt several times v Vargas. I think we'll get the usual fight where Khan puzzles Brook early using his speed and combos to make Brook look a bit pedestrian and then Brook will have him timed around the mid round, catch him and stop him.
If I was Kell, I'd take the fight with the re-hydration clause. Kell's skeleton has a better chance of sparking Khan than he does of beating the best at 154. Plus the re-hydration clause takes this from being a 100% guaranteed KO win for Special K to a fight with a modicum of intrigue. Anyways, Khan looked awful in his last fight. He's shown no power at 147 so it's not like he's knocking out Kell. Worst case scenario he'll light up Kell with pitter patter stuff for 5 rounds then get sparked.
If anyone showing signs of decline it's Khan. Khan knows this is not easy fight and as a dive he wants any advantage he can get. The fool don't want a good honest fair fight.