5.8'' Pro Mini would make me buy it.Ultra Mini isn’t happening because it doesn’t have the space for the cameras. But this might increase the odds of a pro mini in the future. If the regular sized pro is not going to try to keep up with the Ultra’s features, perhaps the Pro’s hardware could be packaged in a mini enclosure.
Yes, the Mini didn’t sell well, but neither has the Plus. This suggests size wasn’t the issue, but price/features. I think a mini Pro, priced between the regular iPhone and iPhone pro would be compelling.
The biggest reason I didn't buy the 13 Mini, was because it lacked the pro materials & 3 cameras.
6.3" which is what iPhone 16 Pro will be, are way too big for me, I'll just run my 13 Pro as long as it lasts, if that size ends up my only Pro motion.