If I remember correctly the restrictions are on the brand not the actual designer. So the new designer of Christian Dior will be a Couturier because Dior is a Couture house. The sanctions are like you have to have an atelier in Paris and employ x amount of people. It's not on the actual designer. That's of course if I remember correctly I did the research a year or two ago.
It is on the house and not the designer, but, Lacroix is one of the few that has had experience working in a house with these restrictions. For example, Valentino was able to participate in couture after he left. It’s the experience that I think would be key here.