You have quite a few spelling errors in your introduction, Earth. Take things easy around here, my friend.
If GT4 was ultra-realistic, I don't think the pick-up-and-play element wouldn't translate. Imagine the children playing the Gran Turismo series and messing around with car handling as if they were Tom Kristensen or Michael Schumacher. I think the handling is enough to be an arcade-style racer while being dead serious about realism. If GT turned into something like Pro Race Driver, Gran Turismo will never be the same again. I guess my issue is that with a whole lot of cars, how can you compare one car in class compared to others? How is the handling of a Dodge Challenger different from a Plymouth Barracuda? A Toyota Supra from a Mazda RX-7? I don't think that it would mean a lot because no matter what happens, a car will always have its strengths and its shortcomings. Ultra-realism will mean that Simulation Tires would pretty much be useless because the tires aren't done up so that they are arcadish. Cars would excessively spin out, even when not trying. I know this having played "Sports Car GT" and downloading cars for the PC version. Some cars were so slippery that I had to completely stop, get it back stable, then keep racing.
My primary issue concerns how people will have to learn to adjust to the new controls even though the new physics engine will make gameplay different from the past three GTs. So, I'm concerned primarily with what people think of a more realistic GT. So much of one that casual racing fans won't successfully assimilate and adjust to this hyper-realistic GT. I don't work for PD, but if I did, I probably would want to have an ultra-realistic GT as a private experiment at PD Headquarters. Of course, I'd want wonderful people like CobraGT to try to bypass security and get this across to GTPlanet. But he's on his own if security has uzis and chainguns and girls in Hello Kitty costumes. I'm just kidding, folks! Anyhow, I don't think it will work. Gran Turismo will be real enough so that even though it may not be SERIOUSLY close to real life driving/racing, it will be real enough so fans will love and respect the series since 1997 (JPN)/1998 (world).