-> Fictional courses/tracks is what Gran Turismo is all about. In GT1, all the tracks were featured was original creation absolutely no real life tracks. But as time goes on, these tracks/courses were either replaced, re-designed, or never to be seen again.
-> Developing new fictional courses are most welcome addition to GT5. However, hopefully before they do that; they should look back and observe these memorable tracks they created in the past.
-> Here are few examples on what I'm trying to describe:
High Speed Ring '90s [ver.GT1/2] (fate: no show in GT3; redesigned in GT4)
Special Stage R11 '90s [ver.GT1] (fate: no show in GT2; redesigned in GT3)
Special Stage R11 Millenium/'00 [ver.GT3] (fate: killed off)
Test Course '90s [ver.GT1/2] (fate: redesigned in GT3)
Grand Valley East '90s/Speedway '90s [ver.GT1/2] (fate: East no show in GT3; Speedway redesigned in GT3)
Grand Valley Speedway Millenium/'00 [ver.GT3] (fate: redesigned in GT4)
Motorsports Land (fate: killed off)
Complex String (fate: killed off; replaced by Nurb-North?)
Grindelwald (fate: killed off or replaced by Eiger Nordwand?)
'Real' Rome Short Course/Circuit (fate: Short Course killed off in GT3; Circuit killed off in GT4)
'Real' Rome Night (fate: killed off; replaced by GeorgeV?)
Seattle Short Course (fate: killed off)
Green Forest Roadway (fate: killed off)
Smokey Mountain Re-Form {North} [GT3]; North '90s/South '90s [GT2] (fate: killed off; replaced by Cathedral Rocks Trail 1/2?)
Pike's Peak Hill Climb/Downhill (fate: killed off or replaced by Grand Canyon in GT4)
Tahiti Road (fate: killed off)
Tahiti Dirt Route 3 (fate: killed off)
Tahiti Maze '90s [ver.GT2] (fate: redesigned in GT3)
Tahiti Circuit (fate: killed off)
Red Rock Valley (fate: killed off)
Mid-Field Raceway The 1st [ver.GT2/3] (fate: redesigned in GT4)