I would love the green hell to be in GT4, but I find it very unlikely that it will be, same with PGR2 - lots of people confuse the old track and the new GP track. It happened with TOCA Race driver loads of rumours - end result the GP track.
As for PGR2 overall, it's going to have to be a massive leap forward from the first one to even come close. Unrealistic vehicle models, worthless damage and handling that was poor even by arcade racer standards. Burnout and Burnout 2 did the job much better on both te PS2 and X-box.
As for Ferrari (and Porsche), its all down to EA. They hold the licences and if they don't want to play then tough. Have a good look at any non EA game with Ferrari and Porsche models in it (Driving Emotion-S is a good example) and play spot the EA logo.
EA are quite happy to sell temporary rights for models if they want to, but lets be fair if you were EA would you want Polyphony anywere near these two.
Anyway I have heard that EA's licence agrement for both run out in about 2004/5 and I'd put money on Porsche and Ferrari heading GT way after that.
Still we can look forward to more RUF's (fingers crossed) in GT4, bring back the Yellowbird.