At this point, all it would take would be to successfully establish the precedent that legal citizens can have their citizenship revoked (which just requires a case getting to the Supreme Court, where the corrupt majority has already demonstrated that they're going to just rubber-stamp whatever Trump wants), then to issue an executive order declaring that [whatever quality] is [whatever has been deemed to be acceptable grounds to have ones citizenship revoked]. It would undoubtedly be challenged, but again, it would wind up in front of the Supreme Court sooner or later, and they'd rubber-stamp it