I have considered flip phones as a replacement for a mini but it's just not the same thing at all when it comes to a smartphone.

It makes the phone less durable for a useless screen size, its pocket ability isn't much better because it is just bulkier (easier to enter in small pockets, but bigger deformation and feel) and it's just less convenient because you have to open it anytime you want to use it.

There is no replacement for a small phone, some manufacturer has to do it.