The MBP is plenty thin enough. Maybe they could shave off an extra .1" but really, it's thin enough.
But as for everyone who says that it's not a professional machine and not fashion statement? What's wrong with wanting to look good? Really? Besides, most of us hoping for a redesign don't even want some kind of major overhaul or something uber-flashy, but are looking for features that are
practical too.
Trackpad:
The current MBP is in bad need of a bigger trackpad to go with the multi-touch. After looking at the MBA, it really reveals the wasted space around the MBP's smaller trackpad. It needs a bigger trackpad for the multi-touch technology to really be practical and useful, and to eliminate that wasted space around it.
Keyboard:
I'm in the camp that fines the MB/MBA keyboards easier to use. I think they feel better. I'm hoping the MBP gets a new keyboard in the redesign. I don't really care what color. And if it's black like the MBA, who says that black looks any less professional? If one's primary concern is a professional machine that does the job, why would you even care what color the keyboard is, or care about other such changes? A keyboard isn't a fashion statement--it's a tool and some of us want (what we think is) a better one.
Size:
I know there are a lot of people that want a 12" MBP, but that's too small for me. I'd like a 13-4" or so for the extra portability

Again, not a fashion statement, just a practical desire.
Blu-ray:
In all honesty, not that important to me, but again something that would probably require a change in design due to the internals that would add some functionality that's important for many people.
Magnetic Latch:
Not cosmetic. Just more practical. (What really amuses me is the people who think this is a problem with a metal laptop. It's ALUMINUM! Not magnetic. And it already has Magsafe. Come on.)
If I got those redesigns I'd be very happy. None of those are fashion statements.
That said, I'd really like to see the MBP get the MBA's tapered edges, so it will "feel" thinner to me. Some of us just want machines WE enjoy looking at, and frankly some of us are bored.