Even if that revocation were followed up by a complete prohibition of civilian ownership of firearms, it still wouldn't do much. Non-compliance, which would be massively widespread, with no feasible way to proactively enforce such a ban, guarantees failure. Law enforcement personnel with arrest powers (that is, the armed ones) would be outnumbered by at least 50 to 1. The military, which might be capable of accomplishing the task (by no means certain), would undoubtedly fragment in response to such orders.
The only practical way to reduce the numbers of guns in US civilian hands is to reduce the demand.