Apple has a second option that may not be open to most other vendors - as they've just demonstrated with the MacBook Neo, they could cut the RAM in half on the budget models. One good cycle of optimising the hell out of their (almost entirely native) software stack, and iOS would once again sing on a 4GB SKU.
I don't necessarily expect them to cut memory on the existing models, but I could well see a 4GB iPhone e/mini showing up to shore up the bottom of the lineup, as the pro models get price increases.
There's a lot of 'ifs' there to be sure, but they'd be fools not to at least discuss the possibility internally and understand their options.