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My feeling is no, that won't happen. HOWEVER we have and are seeing a convergence of the Apple OSs. Already we are seeing the different Apple OSs able to communicate and work with each other. My watch can unlock my other Apple devices. My calls can be taken on any device I want as long as they are on the same network. I think this will continue and only get better, BUT I don't think they will go quite as far as Microsoft seems to be going! Certainly the Watch will always need a special OS.