Well Hifiman is trying to push ahead into an entirely new line (and new generation) of planar magnetics, so it makes sense to phase out the older stuff accordingly I think.
They will most likely still have the resources and machinery for making older stuff on demand, just not routinely; it'd be stupid to just throw away older dies and machines, that's like burning down your old house because you bought a new one.
I understand progress or die, no issue with that. I have no idea how they go about manufacturing the headphones............If they have machines, dyes, etc... or if they outsource the work. In my 49 years I have seen many companies stop offering support of a discontinued product
Good to know HiFiMan wont