Tapered is definitely going to be a target, though I am sure I've seen it on PC laptops for awhile. Obviously, none have been as high profile (har-har) as the MBA.
Regarding design changes on the Pro, I'd do black or dark grey anodized Al, push to make the display bezel even thinner, go to a 3-point magnetic latch, user replaceable HDD in addition to memory, side loading (BD) optical drive.
Thinner? I think we've hit a stable point here at 1", honestly, but if they can figure out how to eliminate case flex, that will be good as well. I agree that they should find a way to lose the plastic duotone edge. I think they kbd is in need of an update, but NOT to the MB board. If there were a way to put a hard cover over the display like some of the PC laptops, I'd be happy about that. Oh, and I'd love to hit that 5 lb mark once again.
I think the design is more like 7 years old (It is similar in many respects to the TiBooks, though there are obviously big differences between the two -- enough to call it a major revision? I can see how some will successfully argue yes, but I think it's too close to call.)