I agree with this 100%. I will keep me 5 for a while... Now that I'm on lte I don't see the point of upgrading again... But you never know what killer feature apple will add...
The days of a "killer feature" are long gone.
That said it's quite possible Apple will ad some amusing, if not very useful gimmick. Deeply addicted to bragging of their superiority, Apple will go to any length to create a headline generating gimmick of the future.
That gives the young easily influenced demographic something to be giddy about. The older buyer is likely to be impressed as well. Apple is a marketing genius.
Regarding upgrade frequency, there's no longer a reason. Apples in the twilight of their fertile innovative era. It was nice while it lasted.
Samsungs the new era creators, innovators, movers & shakers.