If GTA IV fits on 1 DVD, imagine what would be possible with 2 DVDs.
The space issue is not as big as Sony wants you to believe. So, let there be two DVDs, so what? A disc change every 10 hours of gameplay is okay for me. There won't be a big difference in graphics. Space doesn't help, when rest of the hardware it at its limit.
Imagine not having GamePass on your console...