I'd actually have one....
But in seriousness, there's a real gap in the market for a carbon hardtail with modern geometry but not full on "hardcore hardtail" geometry. Right now, we only have true XC race hard tails in carbon, something a hair out of date in the Santa Cruz Chameleon, and then **** like the Rocky Mountain Growler, any Chromag ever, or the Norco Torrent (none of which are carbon, but they're all pretty darn aggressive). We don't really have much in between. I'd design it still around 120mm of travel, but make it quite a bit longer per size, a much shorter seat tube length in each size, a ballpark ~66 HTA or so, and keep the rear end about the same - so you can pick your poison for length back there. Not entirely sure about BB height, probably roughly the same if not a hair lower - the higher BB is part of what makes the stache pretty fun still. You have the option of lowering it manually by running 2.4-2.6 tires. Also a steeper STA but nothing beyond a 75 degree - you want to be able to ride it all day on a variety of terrain - and adjust the frame so the ESTA stays the same in all sizes.