There’s no specific source named other than it’s a “proven source,” but the timing does seem to make a bit of sense. In previous years, Apple would release an update to its iPhone in the middle of summer but it held off on that this year. The decision seems to have worked, as Apple was able to sell a record amount of iPhones last quarter even without a refresh.
The company generally has an iPod-focused event in September and it would be quite easy for it to transition this to its Fall iPhone event. This would make the device available for the back-to-school season and make it a fresher product during the always-lucrative holiday shopping season.
We hear that Apple is planning to sell 25 million of its next iPhones by the end of the year and that actually seems like a realistic figure considering that it just sold more than 20 million units last quarter without a new version to attract users. If Apple does pull out the rumored strategy of tackling the high end and the low end, 25 million may even be a conservative estimate.