How about a fatigue deck where you keep kazakus till the end, when you are sure you have no duplicates left?
I've had a similar idea. Kazakus by himself can be game winning in control matchups, and they're the matches that often go to fatigue or close to it. I wouldn't be surprised to see some non-highlander decks running Kazakus as a late game option.
Depending on the new set, there will be some playtesting to do in order to find out:
a) How many matches against aggro would you lose by playing an early Kazakus with no effect in a non-highlander deck?
b) How many games against midrange/control would you lose by playing an early Kazakus with no effect in a non-highlander deck? (probably not as many as against aggro)
c) With two nearly identical non-highlander lists (some more highlander-ish changes replacements often have little impact on the overall winning rate of a deck), how many games against control are you going to win by having a late game Kazakus?
It will take a lot of testing imho, and of course it's impossible to make any predictions without knowing any of the new 130 cards.