I agree but we might see some average joe's start to upgrade more often with the new carriers upgrade anytime plans but probably won't be as significant.
My GF is the same way, they only reason she's looking to upgrade from her iP4 is because it's starting to die and battery life sucks. She would honestly continue to use it if it weren't for the issues she's having.
My parents also are the same way, the only reason why they end up upgrading every year is because I hand me down my previous phone to them. Their the types to only upgrade when their phone dies.