The marketing purpose is to get people who want a smaller phone to compromise and give up their existing wired headphones, and hopefully buy a pair of wireless headphones, or a pair of Lightning headphones.
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Apple has solved this problem with the "Hunchback of Notre battery".
Hmm, I sure hope that wouldn't be the main driver... but I do get the space thing. I'd rather see them make it a bit thicker, but yea, it's Apple, so you might be right. I still think it's a bad idea, as while I probably use wireless 80% of the time with my iPod touch, I'm still glad it has an actual 1/8" jack (for example, when I fly). Or, sometimes wireless just doesn't work properly. And, I really hate the idea of Lightening headphones... it's one thing to have a proprietary connector for charge/sync etc, but IMO, another for something like headphones. But, again, with Apple, who knows?
If it were something like USB 3 headphones, and there were some industry push to go digital with audio equipment in that way in general, then maybe I'd agree.
And, re: Notre battery, I think that's meant to be a special-case (no pun intended) accessory, not meant to get people through a typical day. That's one thing I highly respect Apple for, design-wise (and hopefully it isn't changing!), is that they realize that typical-day-length between charges is a critical component of any device without swappable batteries. Please, please don't diverge from that!
2GB A8 is on the ipad mini 4 and ATV4, anywho as long as it has 2gb of ram id go for it, they could claim better performance then the iphone 6 series. Although a9 would be very welcome
OK, then I might be *OK* with it, though I'd still really like as much feature parity as possible. The big thing for me is that it isn't a hobbled little-brother product (though having one of those might be good for 'budget' entry product line too), but a reasonable 4" model in the lineup. What exactly they have to do to get there, if anything, I'm OK with... if it's for technical reason, not market-positioning ones (i.e.: trying to cover all the bases with that one model... hobbling it to make it a budget device and not compete with the 4.7").
But, it has to be a 2GB, otherwise, just get a 5s.