It won't fail because of people like yourself. You bought the PS3 just because of GT5. Many will but the game just because it's Gran Turismo.
How can you say you have Prologue and still think it's an upscaled GT4.
Even the standard physics are not quite the same as GT4 physics and the pro physics are not even in the same ballpark.
I wonder what GT5 physics will feel like. It's to be different than Prologue.
As for the cars and tracks, they are the same, so how far can they go into making them look good? I think they're damn good already.
I don't care how good or bad the sound may be as long as they all don't sound the same.
I mean really, how many out there really know how a Ferrari sounds as compared to the game?
I see them around and they sound good enough in the game. Just changing the view you use to drive changes the sound of the car quite a bit.
Try driving the RUF RGT in GT4 and you here almost no engine sound while using cockpit view. Now that is what I want in a game, something realistic, attention to detail.
I believe it's their concept that keeps the game going, along with great graphics and attention to detail. I have played GT4 every day for years (until WRS changed to GT5P). I still LAN race with it every week and it just doesn't get boring for me. I prefer LAN racing to online racing and GT5 is to have wireless LAN so.............

If GT5 were not to be released until next year I would go out and get a new PS2 and play GT4 more than Prologue.
There is just so much content in GT4, and GT5 will have more.
In the USA we say "wipes the floor".
GT5 will wipe the floor with all other racing games! 👍
No fail here.