That has been mentioned before.
And yes - ARM64 is interesting. And one day in the future RISC-V may become interesting as well.
But when prioritizing resources then it make sense for VSI to focus on x86-64 now.
Making VMS run well on one widely available platform is more important than making it run on multiple platforms.
And I suspect that most VMS customer are not focusing on power consumption. If you run 10000+ servers then power consumption matter, but if you can count VMS system on one or two hands then it is not a big number. Power consumption also matters for phones, tablets, laptops and maybe even for desktops - but VMS are not targeting those.
So my suggestion to VSI will be to add ARM64 support in VMS 12.0.