I'm going to run a little with an XL version of the case, just for fun as a thought experiment.
I was looking at various graphic card options. The smallest 2080ti is about 270mm. Expanding to that level is clearly a different case than the MI-6 and not an XL version. The 1080ti mini is far more reasonable at 211mm in length. That means a 21mm stretch for the case. That is far more reasonable, but wasted if all that is done is a case stretch.
Let's look at keeping the proportions the same, in relation to the expansion while also improving 3 core areas: CPU cooling, GPU length, and intake/exhaust cooling. To do this, we'll look at accommodating a GPU the size of a 1080ti mini, a 120mm bottom intake, DTX mainboards support, and a larger CPU cooler/fan.
By expanding the case 45mm (1.37 inches or .09843 Cubits) in length, width, and height the XL version should be able to achieve all of these goals.
The additional width would be sent solely to the CPU side. This would allow for the mounting of both a Dark Rock TF (center fan only) and a Noctua C-14S (bottom fan only). Alternatively, you could mount an L12S with a top mounted 120mm fan. CPU cooling is now substantially improved. Additionally, a 120mm fan could easily be mounted at the bottom.
The height stretch would allow for additional GPU clearance, the ability to mount a DTX boardal and the ability to mount a 120x25mm bottom intake. It would have to be divided such that 35mm went to stretching the mainboard mounting, and 10 mm went to lower the case floor. This would be pretty much solely limited to the ONE X570 board that is DTX right now, but it is a future proofing measure. It would also grant a little more GPU flexability. The problem here is now the PSU would have to be lifted 10mm off the bottom of the case to allow for cables to pass over the 120x25mm fan.
The length increase would allow for up to a 235mm GPU to be installed. This is still far short of the 270mm small 2080TIs, but a good deal easier to deal with than 190mm. Additionally, it would allow the use of the Noctua C-14S on the CPU side, or for more HDDs.
Now these are all estimates, but if anyone has any CAD skills, I'd love to see a size comparison.
Here is the best I could do for free on the web.
comparesizes.com