Lets be serious for second how difficult is it to train for JDS. Lets be honest he primarily punches so I am not sure you need a year to prepare for him.
Cormier himself said it would be easier to train for Jones then JDS because JDS isnt really a fighter who is a big puzzle.
I think JDS is a good fighter but Cain pretty much did what most people thought he would do, take away JDS's striking and he becomes a very beatable opponent.
I am not sure how JDS can change something without revamping his entire game. It wasnt really the wrestling that JDS had problems with, it was adjusting in fight when his main weapon was taken away, he had no other options.