I just used Ferrari as one clear example to illustrate the bigger point I intended, which is the fact that "Jordan" the brand at this point is bigger than Jordan the guy. It clearly derives huge revenue from people who weren't even born, or were barely born, when he was doing his thing. In that sense, my observation has already been proven in the marketplace. People now recognize the name and logo as "cool" and "good" and "desirable" products in the sportswear space, just as they recognize Nike and the Swoosh, Adidas and the three stripes, etc. Even the retro product is purchased by millions of people who never saw MJ wear it live and who never owned that product originally. So again, by definition they are buying them because the product and the brand have become style staples independent of anything MJ ever did in those shoes. In other words, if the majority of Jordan's business came from people like me who were there at the time and are buying because of nostalgia, you'd see the brand's revenue coming in at a fraction of what it actually does. Now, I think we all agree that it's been a long time since a new Air Jordan became a classic, and FOR SURE MJ's exploits in earlier models gives them something extra. But the designs have been the big issue, at least in my opinion. I can't answer for why most of the modern designs have sucked, that's one for the actual designers LOL. That said, they still seem to sell a lot of each year's shoe.
PS: Just since you asked, there are for sure differences in Jordan's and Ferari's business MODELS and clientele, but the basic point about each brand standing on its own regardless of the "founder" at this stage is what is relevant to this topic. And also since you asked, Ferrari's aren't rare because of the attention each is given. Ferrari could make thousands more cars per year if it wanted, but much like Rolex (another monster brand), it limits production intentionally to create mystique and maintain demand--something not foreign to Jordan not too long ago ...