If the new 4-inch iPhone gains all of the features of the A9 chip in the iPhone 6s, it's still unknown how Apple plans to price the device. Earlier rumors had suggested Apple might price it under $500 without a subsidy, but that would undercut the $549 iPhone 6 with a device actually more powerful.
As for the third-generation iPad Air, the A9X processor found in the iPad Pro is a dual-core CPU with a 12-cluster GPU. The beefed-up chip doubles the graphics power of the base A9 processor found in the iPhone 6s series.
So I have a hard time believing that these new devices will be sold as mid range devices. They will be incredibly powerful, more powerful than their bigger siblings because of smaller displays with less pixels to push.
And the iPad Air 3 will be a real power house with 4GB of RAM. And 2GB RAM for the small iPhone 5se will be more than enough too. Very interesting devices to say the least.
And I'm sure they won't be cheap either.