I think that they're accepting that a huge number of people don't upgrade every year anymore.
Carriers in the UK (not sure about elsewhere) have long since ditched 12 month plans where handsets are included alongside the contract, in favour of two year contracts. Then there's the IUP - yes, you can get a new phone after a year, but to "fully own" the device and not hand it back, it's a 20 month loan. (Some carriers have similar annual upgrade programmes of their own, too - many based on 2 year stints).
Then there's the fact that features are plateauing and smart phones are generally becoming incrementally better iterations, with the occasional innovative feature if we're lucky.... So people are happier to hang on to their phone for a year or three (or more) instead of upgrading every year.
I think Apple's pricing is just transitioning to that trend. They can't afford not to iterate every year. a year is a long time in tech and the smart phone industry and they need a phone as current as possible for anyone that may be ready to upgrade now, even if that's only part of the market.
I also think it's partly to do with supply and demand. If people are happy to pay the prices, they're happy to take the money -- but also by having higher prices, they still make money but do lower demand slightly. Instead of having huge supply issues and the news stories it brings because demand can't be met, or quality issues because their suppliers manufacture sub-par quality components and the news stories it brings... They can turn the price up a bit and still sell the number of units they're happy with.