I suppose a lot of the fleet car drivers wouldn't necessarily be 'in to' cars, most see them as a tool for a job, but on the other hand I'd guess there are many BMW, Merc etc drivers who would jump at the chance to trade their rep cars in for a Maserati.
Another factor will be whether the new Ghibli will have the character that other brands simply don't have and be able to move new owners enough that they look beyond their own car and deeper into the Maserati marque.
I'm only on my first Maserati but going on experience I'd certainly buy another, I'd have a factory unit full if I could afford it! My point being that if new owners get a positive experience and enjoyment from their first Maserati they will buy again and its those guys who will be the future Sports Maserati forum members in my opinion. Also possible future owners of our cars.
Either way, I predict a steady rise in members for the foreseeable.
Ru