Look, what I'm saying is that if they were going to get rid of one, my bet would be either the 17 or the 13. Getting rid of the 15 would leave too much of a gap of sizes... though come to think of it, if we are going by processors then the 15 has two models.. maybe it is one of those models that is getting axed...
(anyways, ignoring the possibility that they'll reduce choices of processor in the 15" or 17", which is quite plausible come to think of it)
The argument for it to be the 17" is that it does not sell well enough and that the 13" is their most popular seller (sure, part of that is cheaper, but also part of that is not everyone wants a huge laptop. Go to the MBP forum and find the poll on which computer people thought the ideal MBP. The 17" got the least amount of votes. And since this was just based on people's preferences and not their budget...).
Of course, one could also argue though that there are other options for the 13" that people could go to (I don't like the options myself, but get rid of the 17", they don't have anything comparable. Get rid of the 13", there are still other options. In fact one could argue that there are too many options in that size and apple has ended up competing with itself with the three choices). They could also argue that maybe the plan is for the 13" MBA to be the one to appeal to those that originally wanted the 13" MBP. Maybe the next update to the 13" MBA will make it more comparable in specs.
Actually, I'm going to say my guess is they get rid of the i5 17" (but keep the i7 in the 17"). I mean it's supposed to be the power horse of the bunch and not budget minded so maybe they figured you want the 17", you want the faster processor.
(of course this is all assuming that by model we mean processor speed. Cause if it is just by size of laptop, if they are introducing four models, that means they are adding a size).