I think having a second, plus size case would be killer, microATX support, since nobody seems to want to make DTX motherboards, also I've seen a few utter bonkers mATX boards with workstation/server sized sockets, or I'd have asked for compatibility with that form factor. A 120mm rear fan, 280mm rad at normal thickness with normal fan thickness on the bottom and side, with option to invert the motherboard, keep the ODD, use a smaller panel to have or not have it available to use, so both panels can ship with an order. The added height of the case can be used to add a lot of drives at the front, below the ODD bracket, mounted at 90 degrees, to take up a bit less vertical space. Keep the IO, maybe add more with the added space. Also a bigger GPU bracket may be needed, it looks like GPU water blocks might get quite heavy in the near future.
And for no consideration (No one seems to be of sound enough mind to consider this anymore), a FULL SD card reader slot, along the same area of the frame as the ODD bracket goes for accessibility.