Also interesting, the M4 Mini has the flash storage on a replaceable module, instead of being soldered to the motherboard, although the NVMe controller is still integrated into the SoC. iFixIt and others have already posted videos showing that the flash storage is now upgradable. > M4 Mac mini Teardown - UPGRADABLE SSD, Powerful, and TINY https://m.youtube.com/watch?v=rtdGxBeSkz8
"Upgradeable" is too big of a word here, specially considering that they're using different form-factors even between the models released on the same year (e.g. pro vs non-pro) ; and also different from models released on the previous year (e.g. studio). This almost certainly means that next year's model will also use a different interface, so you won't be able to upgrade your storage at all.
I wonder if 3rd parties will start selling them. If the memory controller is in the cpu, there’s no reason for the little board housing the ssd to have any proprietary chips…