Very hard to predict due to the fact he has been inactive for a long time. The Alexander saga will have no doubt set him back. IMO Brook trained well up to the Alexander fight and maybe the trainers realised he wasn't ready.
Apparently Brook is looking sharp and is in great shape. Mentally I'm not to sure. I would say either early KO or SD for brook.

I just hope he does a number on Jones and Hearn puts him in with a more decent fighter before maybe a showdown with the winner of the Khan/Alexander fight (if that is made obviously).