Infina, in an old thread, I said the exact same thing about Ferrari and Porsche. Is it a great shame not to have them into the game as big as GT4 is? To me, here's a little different side of things.
Without Ferrari and Porsche, I think the game will still be sensational. I'm sure that when KY said that Ferrari and Lamborghini are not impossible, in a way, I kind of don't care about the two makes. They have a long racing history, but I'll still stand behind PD here. I think today (considering it's May 14th in Central Daylight Time) is the last day of E3, so maybe what someone else said is true- Polyphony Digital MAY have some big news that will get our blood pumping and our hearts racing (literally). So while PD's task of securing Ferrari and Lamborghini has probably failed for GT4, I tend to look at it this way.
First off, we got a lot of cars dating back to the 19th Century (when the automobile was born). Next, we have a lot of tracks most likely spanning the world with Africa and Australia possible (Kyliami would be a good choice for Africa, if not a Safari or Dakar rally). But to me, I don't really care for Ferrari and Porsche in GT4 as its stands, but for the most part, just hope they will be in GT5. And if you ask me, Ferrari and Porsche's abscence won't hurt GT4 too much. But look at it this way. MAYBE there is a chance that there may be a Ferrari or Porsche "teaser" to unlock in the game, like the Mercedes-Benz CLK-GTR of the all-good-ideas-but-bad-execution GT2. And as I said, GT2 had the most easter eggs of any of the GT games. I just hope GT4 won't be as bad in terms of cars and tracks.