The proposed 777-10X looks like a standard 777 was pulled like taffy.

That's only true for the longest variant of the original design. I drew a line and put a wheel (the app wouldn't let me shrink the sticker enough) where it would be if what you said was true for this model. They dont change that angle when the jet is lengthened or shortened beyond the additional offering https://preview.redd.it/x41mazrb3igg1.png?width=640&format=png&auto=webp&s=f089324906042d84029a9d552c176d3a1a0611ca You can see that the landing gear would have to place the jet an entire fuselage-height off the ground. The lowest point on a 777 (i know from walking under then) is roughly about 6.5-7' off the ground. This design would raise that to nearly 20 feet... they're not doing that In fact the stretch 737s have the same issue. Their landings have to be way faster than the original Vref to avoid tail strikes.