Not knocking the Government, this is going to be a very difficult job and to a large extent will have to be type-driven rather than whatever someone is calling the 'breed' at that point of time.
It also has to bring in a zero tolerance behaviour approach as well, surely? There is no legal interest in dog on dog (or other animal) attacks at the moment, but I think this surely has to be brought in to play too. The attacks that these types make on dogs maim and kill, they are not normal dog spats.
I would change direction to avoid passing any I might meet on a walk - thankfully extremely rare round here - perhaps they are friendly, but by Christ I'm not going to be the one to find out, the thought of my dogs being ripped apart in front of me makes me feel physically sick. (Let's not even think of the poor man yesterday, and those who witnessed it and had to manage the aftermath.)
I love big dogs, I am not a hand wringer about normal breeds, but this type of dog is just an incomparable problem to anything we've had before at scale in this country, and the problem is growing. Anyone who can't see that, proportionally to their population, they are an issue is frankly a bit thick.
The existing population won't be rounded up and PTS when the law passes, but by God there should be no tolerance for any dog causing issues, including those that aren't contained securely and escape their homes. If these owners care so much about their dogs, they should demonstrate good animal husbandry and ensure that this doesn't happen, and if the dogs escape/off lead on walks/un-muzzled/un-neutered or cause any issues at all in their community, they should be seized.
I also think that it should be made illegal for rescues to re-home any dog of this type - sad for the workers, but let's reduce their population where possible and not pass on dogs that are as likely as not to have issues, or they wouldn't be in rescue in the first place.
Oh, and any consenting adults who currently own these dogs, let Darwinism plot your future - but anyone who has them in a house where children live or visit, shame on you.