As far as higher ISO sensitivity goes, I think there's a lot of room for improvement. Not for 'normal' day to day applications, perhaps, but when shooting indoors with available light. There are a great many dim indoor live music venues where F2.0 @ISO3200 doesn't even come close to getting a decent exposure - an extra 4 stops would be really nice i.e. I'd be quite happy with something around ISO51200 with s/n ratios that are comparable to modern day ISO1600 images.