Mac Mini in current form is, and in future will be NUC type offering from Apple, so better get used to its current form. What I believe Apple might do is cut the trash can in half, redesign the thermal core a bit, bring quad core 35W CPUs(Skylake, for example), with single GPU that can fit in the case(Fury Nano for example) and SO-DIMM memory like are in iMac. Offer it for prices starting at 999$ for simplest config like with 2.2 GHz CPU only, 256 GB SSD, 8 GB of RAM, etc, and give ability to build it over it.