I find that often people ask this question on whether such an "entry way" needs a mezuzah or not.
From what I see here there is no mashkof what so ever as well there is just a regular plan wall on the other side opposite this, not even something protruding out. Is there any reason to yes put a mezuzah here (any shita or chumrah?) As well if the mezuzah has already been put up should one leave it up or may it be taken down? I know in the past R' Shammai always says (pashut) that there is no need for a mezuzah in such a case.
The other question that was asked was this one:
The same idea, no mezuzah on the other side (just a plain wall), and not mashkof. Even if there would be some sort of mezuzah on the other side, still there is no mashkof.