Constitutional considerations aside (since all implementations seem to run up against one or two amendments), the most likely route is probably to force complia

Constitutional considerations aside (since all implementations seem to run up against one or two amendments), the most likely route is probably to force compliance by tech workers/companies when presented with a warrant (see: the law rushed through late last year in Australia). One basic implementation is that after some closed-door conversations, your specific instance of WhatsApp receives an update which either compromises your keys or performs some background E2E of your plaintext conversations (as stored on your device) with whichever government/law enforcement agency made the request. Rather than adding the government as a third party to all communications at once, this is a nice easy first step for them to take.