Johnnypenso
The risk is for the fans of the series, that PD will spend a huge amount of resources modeling a gigantic track for a car game at the exclusion of other tracks, much more suited to circuit racing.
Its a matter of perspective I suppose. I like Watkings Glen, Road America, Mosport, Sebring, Long Beach, Bristol, Charlotte, and I still havent even left North America. Would I give up 5 of my most wanted tracks from across the world for just the Isle of Man? I wouldnt even have to think about it.
While other courses may be better suited to circuit racing, Isle of Man is better suited to time trials that really test your bravery (no runoffs here), a higher sense of speed thanks to narrow roads and close scenery, and cruising.
Who is going to enjoy cruising around Waktins Glen moreso then the Isle of Man? Who is going to get a higher sense of speed at the new Hockenheim? Who is going to enjoy the challenge of learning Long Beach more then learning the Isle of Man course? Isle of Man has attributes a traditional circuit does not have.
Is it any worse then the Nurburgring in terms of racing? The Ring is 13 miles long and the long back straight is the only real passing opportunity. I've played follow the leader throughout the whole course behind a car I was quicker then because there was no where safe to pass.
A popular race distance online is 2 laps at the 24 hour Nurburgring course. Thats roughly the same amount of time it will take to complete one lap at Isle of Man. So its not completely useless as a race circuit.
Johnnypenso
The reward is potentially more sales for GT which of course means nothing to the fans complaining of poor gameplay for 2 iterations of the game.
I dont think the two are related, though. They can still improve gameplay and add this course. The track designers devoting more work to a massive project wont affect the AI and sound programmers.
ShiftingGears
So do you want gameplay issues fixed, or do you want PD to maintain sales? You seem to prefer the latter. That said, they are not mutually exclusive. I would also like to point out that GT5 and GT6 have had plenty of features, delivered or not, whose primary function seemed to be to create 'buzz'. That does not seem to be working out so well for them at the moment. So really, including another feature with little in-game utility would just be PD continuing the trend they've already set.
I prefer both. I've been very critical of PD's marketing of the series for the last few years. I didnt agree with making the LLC Rocket the poster car in most advertisements. Or touting a new physics engine and tessellation as the biggest upgrades.
Isle of Man to me is like them announcing the Nurburgring for GT4 all over again. Its huge, and advertising done right IMO. And bikes? Thats going to catch people's attention, guaranteed.
And I'll just leave this here