Some more thoughts after reading some of the comments.
Dual HDD/SSD setup: I really don't picture this happening. They are great right now because SSD's are pricey in the large size, but moving forward their will be less and less of a need as cost goes down for SSD and capacity increases.
Now, I know they have the iMac with the ability to do that configuration, but it's really in a different market. With the iMac, the standard configuration is just 1 HDD with the wasted hard drive bay free for an SSD. Even though the 13" is labeled as a "pro" machine, we all know the dominating market aren't exactly pros users. The general consumer, not likely those of us on macrumors all the time, isn't going to want to manage which drive to add stuff to and mess with file placements between HD and SSD. I don't see that fitting in with the existing thoughtfulness of apple and their products.
If they try that same setup with a macbook pro, it's going to increase the cost of the laptop. It also wouldn't make much sense as a build-to-order option. They aren't going to want to ship the laptop with an empty slot for a hard drive. I've yet to see a laptop where they purposely would want empty space in the standard configuration. They will keep the SSD in one location and either shrink the size of the laptop, add battery or use the needed space for the cpu/gpu.
Redesign: I don't think there is really anything wrong with the design right now. If anything it would be a minor design change due to the removal of the ODD. I still imagine the aluminum enclosure, only with a few different line changes in the casing. I am sure there will be some complaints about the minor adjustments if it does come to fruition, but like the iPad...there's only so much that can change.