I think a new Triaxis would be awesome, but for it to actually work as a marketable product, it would really need to represent the tones of Mesa's entire catalog, not just a handful of Marks. You'd need everything from the cleans of the Fillmore and Cali Tweed, as well as the Mark VII's modes of the Crunch, IIB, IIC+, and IV, and the Orange and Red channels of the Recto, maybe even throw in a channel from the Badlander too. Not to mention you'd probably want a better control mechanism than the old UP / DN membrane buttons and LED displays on the front.
Oh and you'd need a much, much better representation of the GEQ. The OG Triaxis' Dynamic Voice control was and is still awful. I've never once used it on a higher setting than 1 (which just gives you some bass boost and nothing else, pretty much). Instead I've always used a separate outboard EQ. To replace the Dynamic Voice, you'd either need a separate section of the front dedicated to just EQ and the ability to tweak each band, or a way to implement "pages" for each patch and have the 2nd page give you control of each EQ band.