In this weeks MacWorld posting they note that Apple’s iPhone sales have stalled. This is not to say there isn’t good demand for the phone. It’s just growth is nothing like the past.
One reason pointed out is that the field of iPhone sales is maturing, I would also tender a bet that the price of the new phone, which seems extremely high by past standards, has slowed things down.
Might Explain Rumours for an SE
Apple, at the same time, is rumoured to be coming out with a 4″ model, similar to the iPhone 5s but at greatly reduced prices. This would encourage sales of new phones to the budget conscious without eating into the sale of the high end iPhone 6s. Regardless, the March 21 event is shaping up to be something of greater interest.