I found the part in bold extremely amusing. You are simultaneously saying that nothing is impossible, and that nothing is not possible; and you continue to say that various things must be and cannot be, as if there are no possible alternatives, seemingly missing or ignoring one (or more) meaning(s) of what you've said. Such is the nature of making a point, I suppose, but in a discussion such as this, where the topic is such an abstract concept, I don't think there's any context on which to base the exclusion of any interpretations.
It seems to me that this topic is more a matter of defining nothing than anything, so my answer will be focused on that. (All this nothing is going to be fun)
I think nothing is a matter of perception. Going back to the thread you linked as proof that nothing cannot be aeturnal...
Ignoring (but not really) the obvious point of 'give me an example of a real life aeturnal thing', it can be said that air and space are indeed nothing, from the perspective of the person who does not know what they are, at least. We both see the same thing, but we call it by different names. If we're speaking the same language, this means that one or both of our names has a subjective element to it (or at least one of us is just wrong, but let's ignore that for now). In this case, I think it's fair to say that 'nothing' can be taken to mean 'that which I do not know of' or 'that which I do not recognize' or (best of all, perhaps) 'that which has no meaning to me'. After all, even if you tell me there's air in that jar; to me, air still only means 'the nothing I see in that jar', if not 'just something that guy made up'.
Using this definition, anything can be nothing, and nothing can be anything. It goes without saying, then, that nothing can be something, and vice-versa.
...I had more to say, but I've lost my train of thought. I'll just leave at this, for now.