The only reason to care about Haswell processors is if you're looking at integrated graphics as on the Air. The processor performance increase will be imperceptible compared to the Ivy Bridge.
I have heard no rumours of a 17 inch, but I wouldn't really expect to. Maybe "doubling down on secrecy", to quote Tim Cook, is working!
However, what I have noticed is that a lot of top DJs and Film Producers have them, so there is clearly market demand. It's kind of an aspirational product as well, people who want one but can't afford one settle for the 15 inch, so it kind of drives 15 inch sales.
On previous design change refreshes Apple released the 15 inch model first followed by 13 inch and 17 inch models later. The margins are almost certainly highest on the 17 inch and lowest on the 13 inch.
Finally Apple only has a very small number of laptop models, given laptops make up the majority of sales it makes little sense to reduce customer choice.