What do you mean by classic 15" ??? Do you mean non-Retina? It is possible that Apple might offer non-Retina MBPs with Haswell, but I would be surprised. I'm not even sure that Apple will offer non-Retina MBAs with Haswell.
I disagree with the premise that the entry-level price of the Retina MBPs must match the current entry-level price of the non-Retina MBPs. Also, if we look at the prices the resellers are now charging, it seems the costs are coming down as the yields are rising. I don't expect any large margin drops, either soon or farther into the future.
Considering how the Microsoft Surface and all other tablets of the sort you describe have been a terrible failure in the market, it would seem that Apple will not go there but rather will continue to produce what customers want.
It's already possible to use a bluetooth keyboard with an iPad. Some 3rd parties make iPad cases with built-in bluetooth keyboards, though only about 1% of the iPads I see are used with keyboards.
Yes, it's clear that the old, thick, and heavy MacBook Pro with the internal optical brick will go away. I guess it will happen with the introduction of Haswell processors, but it might have to wait for the introduction of Broadwell processors. It will depend on relative sales and on Retina display yields. When Apple are able to consolidate their MacBook Pro line by dropping the internal optical brick, it might be an opportunity to introduce a 17" Retina MacBook Pro....