It seems that Apple will make use of the more recent LPDDR4 technology that would pave the way for doubling of the bandwidth at 34Gbps, all the while doing so without having to consume any extra juice. Right now, both the iPhone 6 as well as the iPhone 6 Plus will arrive with just 1GB RAM that will make use of the older LPDDR3 technology.
One thing to take into consideration would be the cost though – as LPDDR4 at this point in time, would cost 35% more compared to the older LPDDR3. Not only that, there are also production issues to worry about, although that has been largely worked out by Micron, the vendor tasked with churning out such memory chips – one of the few, of course, as Apple does not place all of their eggs in a single basket. Just what do you think the iPhone 6s will come with other than double the RAM?