Re: theoretical non-event
My Desire S went from Gingerbread to ICS, but this wasn't over the air, and it wiped the phone in the process. My wife's Xperia Mini never got off of Gingerbread.
I won't claim that these two phones are representative, but they do balance out your examples.
My Nexus 7 gets all the updates, and I slightly regret letting KitKat on.