A RTX4090 won't fit in any SFF of 7L, let's be realistic (and a RTX3090 is already too much for this IMO). I like the z-case p50 design for the small footprint (being almost smaller than my polycarbonate case) and I would like to keep it that way.I would like support for SFX (and SFX-L) PSU, and longer frame to support larger graphic cards in addition to the suggestions mentioned above. USBC cut out would also be nice. The RTX 3090 I had didn’t fit into the P50 along with various 3080 and AMD cards due to length issues. I ended up having to convert it into a water cooled build, as the backplate fit into the case. My enhance flex PSU can only handle so much (had to severely undervolt and underpower my 3090 to get it running stable) and with future video cards being more power hungry, SFX or even ATX PSUs will be needed to support the demand.
I would definitely prefer to keep it as FLEX PSU. Sure wattage is limiting but we already have more options for bigger console-style cases for SFX and SFX-L.