I'm not a rom hacker or game designer by any means, but I've always felt that making HM moves actually usable as incentive to use them was a good balance on how to incorporate them. I recently played a rom hack where I also edited cut to essentially be the same thing as slash (70 BP, 100 accuracy, high critical hit ratio), another one I've always thought could work solid be making rock smash just fighting type quick attack: priority instead of chance to lower defense).I think the focus will be more on making HMs balanced to where you'd want to use them in battle, while also allowing them to be overwritten by other moves if you want to learn something new.
The required Cut trees have been scripted to be permanently removed once cut down, so after those, Cut is entirely optional. I'm a fan of what I did with Surf in the old orange where it became a water-type Return and may do something similar for other HMs.
I'm a fan of exploration and HM obstacles do add to exploration, so I don't think I will be removing them, just supporting other playstyles by adding some QoL to how they work.
Really excited to see how you incorporate that and am really looking forward to this hack!