This argument occurred to me today as I was thinking about my previous post. A lot of us are familiar with the S5 axiom stated as, "if possibly necessarily p, then necessarily p." However, another aspect of S5 is this: "if possibly p, then necessarily possibly p."
Let's take w1, then, where purportedly nothing at all exists, not even possibility. Considering some other possible world w2, where at least one concrete object X exists, it follows that: if possibly X, then necessarily possibly X. Now, since whatever is necessary applies to all possible worlds, the possibility of X must obtain in w1. Taking this one step further, we can apply a rather benign causal principle to the argument: if possibly X in w1, then necessarily something concrete exists in w1. This is because nothing concrete can come into being apart from some other concrete being. If X doesn't come into being, then X exists by itself in w1. Thus the feasibility of ontological nihilism is defeated.