As a personal point of view, I would say that apart from things like "the Americas cup", around the world races, etc, there are no classes of sailing craft that would fall under the banner of "professional classes", there are though professional sailers and non professional sailers. The professional sailer is by definition, one who "makes his lively hood or living solely from sailing and its peripheries, as a business".
If you relate “professional classes” of sailing boats to another sport where there are recognised professionals such as automobile racing, then you would have to say that “cart”, “formula one”, “motto GP”, and their like are fully professional, but an enthusiast who goes out on a Sunday afternoon and races his “home maintained” car in a hill climb, off road rally, Targa, etc, even though he may receive “prize money” or even an “appearance” subsidy, still cannot be justifiably called “a professional” competing in a “professional” class/event.
There is a vast difference between a professional “class” and a class that is run/administered “professionally”. One refers specifically to the remuneration and the other refers to the “excellence/diligence” of its organization/administration. Similarly with sailers, one doesn’t have to be a “professional” (money wise) to sail “professionally” (conduct and ability wise)
I am not sure how it is done elsewhere in the world, but here any/all sail boat class associations are registered as "non profit" organizations and as such they are all (class associations) non professional I.E. amateur by law, (even the Tornado association)