I can see two possible outcomes.
1. Apple will reduce pricing at septembers iPhone-event, by $100 or so across the board (def not more).
2. MSRP will remain the same, but Apple will collaborate with Best Buy and other 3rd party retailers by lowering their margins for specific sales events. This is what they are doing here in Europe, allowing retailers to buy large stock of products at heavily discounted prices, so retailers can sell MacBooks and iPads far below MSRP, but only for a limited time (e.g. back to school, Black Friday). This has not really been the case for iPhones, but I think it will be!
I think we will see more of the latter between now and September, especially in Europe. It's a good strategy by Apple. The "Sales" cannot be tracked to Apple, it only looks as if retailers are discounting the products, whereas they can still keep charging the MSRP price at their Apple Stores for people who are less sensitive to price and prefer the "Apple purchasing experience".