The radio coverage all through practice week always included the MGP when they mentioned the event as a whole. e.g "The Isle of Man Festival of Motorcycling, Classic TT & Manx Grand Prix". If "the powers that be" wanted rid of the event, they could do it much quicker than ignoring it until it went away.

The Classic TT brings in the big names, which gets visitors on to the island, which may ultimately be the thing that keeps the MGP going, not the other way around.