I think aerials has already shown how far it can progress, but freeskiing will have a more interesting evolution due to the comp scene. There are people who could quad flip/cork/whatever, 1800s, and all kinds of other madness, but I don't think our culture will tolerate sacrificing style for numbers. In the past 5 years or so jumps have been getting bigger, so it's been possible to do a double cork 12 and make it look pretty nice. T-wall does 9's effortlessly and smooth, while back in the day 900 was a number that would turn some heads.
I think that bigger tricks are good in that they separate amateur from pro, as well as push the limits as to what a rider can make look nice.