Just wanted to state, that last part is in no way unique to Apple. Maybe in your experience, but IMO John Lewis is better than Apple.
John Lewis is a department store. and yes other retail establishments have excellent customer service. But in the realm of needing to get your phone fixed (talking about accidental damage) pronto I love the idea having Apple stores across the country.
----------
Apple finally gave users a big screen phone that a lot of people were waiting for.I know my close friend was waiting for a bigger phone for a while and left his note 3 for a 6 plus.
But don't think Apple will have this same growth and profit next round.apple right now is where samsung was when they hit the streets with the s3.now that everyone got a big iphone there won't be a huge demand this time next year with the 6s and iPhone 7.
You can quote this and remember it when apple hits a saturation point like Samsung did next year.
There still is a population os 4s, 5 and 5c/5s that would be ripe for the 6s or 7. But generally I think you are correct, about the universe of those who will upgrade.