I am still using my 13 Mini. I got it, because I knew that it would be the last Mini Apple does.
I plan to use it, until I need to charge the battery every 15 minutes.
Just so you know, the batteries are replaceable ;)
Same boat, though with battery replacements, I think what will actually do me in and force me to downgrade to a newer model will be when they stop supporting OS security upgrades. I'm perfectly happy to keep replacing the screen protector and battery until that point.
Then replace the battery and carry on using it?
I have a 13 mini that is hanging on by a thread and you will pry it from my hand (because I can actually hold onto it). I'm actually considering finding a refub because I prefer my old-fashioned artillery to the 6.1".
The larger phones barely fit in pockets, fit poorly in running packs/biking gear and are just generally inconvienient for being active with them.