I'm patient. The 5S will be a fine upgrade for me in the meantime. I no longer live at the whim of Apple's upgrade cycle. iPhones are quality products with plenty of life in them. Even after a few years.
20% is understandable. I was poised to upgrade when the 6 / 6 plus came out, but there's no way I'm walking around with a behemoth phone in my hand. If I decide to upgrade this year -- and Apple doesn't make a smaller version of the next iPhone -- I will buy an unlocked 5S.