Cases in point:
The Discovery Channel
The Learning Channel
Both have grown fat with "Edutainment" and just flat out mind numbing shows about choppers and poker. Dirty jobs is the only winner, being equaly interesting and entertaining. Top Gear is very interesting...in Britain. Why? Because it's british. I live in america, I know what the cars are like here. I've never seen a Megane or Spyker. Plus its rude and funny. Here, they are going to film their own version in AZ, likely to be poor entertainment and uninteresting. They cast a bloody reality show twit for gods sake.
Compare the popularity of NASCAR to the lack of intrest in "boring" F1, ALMS, Speed GT, and WRC races. Entertainment disguised as a sport is tenaciously embraced, while real motorsport that happens to be entertaining cant get a time slot.