Firstly, I don't see what bitcoin miners are producing other than bitcoin. Heat, perhaps? Bitcoin can be part of their revenue, but it is their production of it that pays their bills. Let's get this in order: first, their production (they are producing bitcoin and heat, nothing more) drops by 50% on the bitcoin front.
Why do you continue to persist when it is evident that it is their revenue that would fall first? Not until then miners have any reason to cut production (effort and time wise), since that would mean losing profits. They don't care so much about the amount of coins they produce per block as about the revenue they get per same block...