For people still not getting why Apple would do this, it's simple. It's the same reason they did the iPod Mini back in the days, the same reason they're doing the iPad Mini now and it all goes down to a single word that's become one of the biggest factors in trying to run a healthy business :
Growth.
Take that word in. Learn what it means and try to see Apple's moves as aiming towards that goal. Profitability, to investors and the markets, means little with the absence of growth. A company can be profitable yet be said to be "dying" if it's not showing it. For Apple, the last few year's have been about utilizing the iPhone to make this growth happen, and its come to the point where the iPhone is the main driver behind their growth and revenues (over 50%!). The US market has been a big influence in this and is their primary market for the iPhone.
Now consider this other tidbit :
http://www.businessinsider.com/us-smartphone-market-2012-9
Although real-world data rarely follows a curve as smooth as the textbook diffusion curve above, it seems reasonable to conclude that 2011 and 2012 will mark the peak years for smartphone growth in the U.S.
The smartphone platform is about to reach maturity in many first world markets like the US. To continue on a path of growth, Apple must open itself up to newer markets or different segments. That, or it needs to kill off competitors. In light of all of this, if you still don't understand the iPod Mini strategy behind these "cheaper iPhone" rumors, I don't know what to tell you, those are just the market realities.
It doesn't matter if its this year or the next or in 2015, at some point, Apple will open up the iPhone platform to other market segments and other markets in order to reach a much broader audience and sustain their growth. They will milk it until mobile phones start declining and then will move on to tapping other markets to keep their growth going (like they are moving away from the iPod as it is a shrinking market, which can be witnessed in the lesser emphasis they put on the line-up).
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Pah! beggars will have iPhones next and all exclusivity will have gone.
The exclusivity was gone when Apple started selling multi-million units per quarter. Owning anything Apple hasn't been an "exclusive club" since Steve came back and brought the company back to health.
If anything, the "Apple exclusivity" was killing the company. You really want that back ? I sure don't. I prefer healthy, mass-market, "everybody and their mother owns Apple stuff" healthy Apple to "I'm some kind of freak that owns an Apple product and you can't" dying Apple anyday of the week.