Given the hardware between the One and the MAX are almost identical it is expected to be easy for dev's to port the code for the MAX from the one.
me and @deagleone
actually tried flashing the One's kernel and the phone boots, the only thing that was broken was the WiFi which is a because of the different hardware.
The One was the phones which received a lot of dev support and has variety of custom rom's from AOSP to Sense
HTC One MAX ||| HTC ONE > HOX+ > Nexus 7 > HOX > Xperia Arc > Xperia X10 Mini > K810 > K550 > K750