The justification for the pardon is, particularly in making it so sweeping, that it is to counter political attacks via criminal charges, both prior and potentially after the President’s term of office.
This same argument can of course be used by any future President, both for the President and for any immediate family.
Other than a Constitutional Amendment, is there anything that can be done to keep this from cycling out of control, so it doesn’t become routine for the President to issue a self-pardon and a pardon for any and all family/friends when exiting office?