I don't see the mini being treated (price wise) like the very first iPhone. If the 6% in sales were in the neighborhood of 50% and Apple stopped producing for some reason, I would expect third party market prices to soar. As is, the mini is a great phone but, it's nothing unique or special.If the 12 Mini is indeed a one year model, hedge your bet and buy one today and don't touch it.
I suspect the increased value of an unopened iPhone 12 Mini next year would be substantial.