On a serious note, I do not think this would be enforceable by 2018. The necessary literary paraphernalia does not exist to support such a decision. Even if such a decision is upheld by the SC, I think they will give a transition period which should be at least 3-5 years and even after a choice should exist. Candidates should have a choice if they want to attempt the paper in English or in Urdu.
Hence I reiterate that this would not be the case in 2018 so everybody relax