by that reasoning then, it'd make more sense to add a translucent EVF screen on the same plane as the focusing matte, most likely after it along the optical path, ie. sandwiched between the matte and the prism.
It would then lose a small amount of light transmission in the OVF system having a clear/transparent LCD type screen in the way too.
Surely tho, if there as indeed a switch for an EVF, that the switch would also act on a refocusing mechanism to account for any focus discrepancies.
Alternatively the EVF LCD component could be made deliberately unfocused to take into account that focus distance issue, thereby making in focus at the ocular.
For them to remove the built in flash, the implication must surely be that the prism is probably going to be larger in some way.