Well, we will see. I think we just have to agree to disagree, we're pretty much just pushing our own opinions anyway and there are points in both of our favors. In any case, I'm fully convinced that the internal optical drives will be gone from the MacBook Pros within the next year, so your claim that they won't be gone "in the next couple of refreshes" seems to indicate that you believe that it won't happen until we're well into 2012, which is a long time to wait (for you to be proven "right" or for me to be totally wrong).
As a final word on this matter, I'd suggest that everyone take out a CD jewel case and place it on the top of their MacBook keyboard. Note that it takes up almost 1/4 of the surface area and nearly that much of the volume of a 13" MacBook. Do you really think that having that much space taken up by a device that you seldom use is a good thing? And it makes even less sense for a mobile device that will most likely never have a need for a CD/DVD when away from the home or office.
As far as differentiating the current line of 13" MacBooks, the Sandy Bridge processor is going to do that. The MacBook Pros will have Sandy Bridge, the white MacBook and the MacBook Airs will have the Core 2 Duo. That's going to represent a huge gap in performance between the products. You're not actually believing that Apple is going to put the Sandy Bridge CPU in a soon-to-be-released version of the white MacBook? We're not going to see a processor change in the white MacBook until both the Mac mini and MacBook Airs are ready to do the same. That will be the telling event, if Apple comes out with a Sandy Bridge-based white MacBook then you can be fairly certain that the white MacBook will be here for several more years. Otherwise, it's axe-time for the white MacBook. As for the MacBook Airs, they will probably transition to a low-voltage Sandy Bridge part within the next year, but that won't happen before the latter part of 2011 or maybe not even until early 2012 at which time Ivy Bridge might be the logical choice.