Good point. I suppose it depends upon whether you could really achieve that by replacing the existing CU with "nothing," not even a junction box and a new length of cable to connect from the existing incoming supply cable to the existing sockets. Of course, if you could replace the CU with absolutely nothing to achieve it and that would be non-notifiable, but replacing the CU with a junction box etc. would make it notifiable, that would be ridiculous, since adding those same things to an existing circuit is not notifiable.