Perhaps Apple could avoid that by launching the new MacBooks a month or so later than the new Pros. Most students probably bought the cheaper MacBooks while the Pro line is also marketed towards professional photographers, music mixers, and business execs. New iPods, on the other hand, are more likely to launch along with the redesigned Pros as they were essentially free with the back-to-school deal.
I believe the spy shots that show new MacBook Pros getting tapered edges like the Air and a long removable battery that, when removed, gives access to the hard drive bay, like the MacBook. Then of course they'll replace the current flush keyboard with the Air's indented keyboard of black, backlit, more clicky keys and the Pro's mechanical screen latch (which still irritates me to this day) will be replaced with magnets, like the Air and MacBook.
As for the MacBook, I don't buy the unfounded notion of moving to an aluminum case. Yes, Apple has been transitioning to aluminum for a while now, but they also use these different materials to differentiate their premium and high-end computers (MacBook Air, MacBook Pro, iMac, Mac Pro), from their budget/consumer-oriented computers (Mac mini, MacBook).
The Mac mini and MacBook's use of plastic polycarbonate keeps costs low and weight low, in addition to making their higher-end, all aluminum Macs more desirable. So, in continuing their move towards tapered edges and avoiding buyer confusion that could lead to product cannibalization, they'll launch a tapered-edged, polycarbonate MacBook in the same black and white color options, with a LED backlit display, perhaps an oversized Multi-Touch trackpad (which is likely to come to the Pros as well), and of course, the usual under-the-hood CPU, GPU and storage enhancements. If they could get the price down to $1000, that'd be even better.