In this case, never means exactly that: never. Not in my lifetime. Not in yours. Not in my kids'. These are not the design constraints that will ever change for conventional optomechanical scopes. A run of the mil consumer will never be able to have a clean enough environment to do that, the metrology tools to get the focus and alignment right and the equipment to purge the scope after opening it up.“Never” to me is not in my lifetime and not under current design constraints.
-Stan
ILya