For core version 0.12... why? Presumably to predate all segwit code and be compatible with BU? Since it's a hard fork proposal independent of segwit there is nothing that would prevent this from being made for core 0.14. BIP100 was the most popular choice amongst mining pools when it was first proposed. Don't be surprised if it makes a surprising comeback now. If this was coded up for core instead of BU without any other changes it would be very popular very quickly...