Dear Felix,
Though from a different reasoning than yours, I arrive at some of the same conclusions you have.
I explained in my reply to the FQXi recent article titled "Killing Time" that I find no reason to believe that time is anything else than a purely relational concept. It follows that the union of purely relational concept, that is, with space, a physical aspect of reality, is a mistake. Thus, not only can quantum theory do without space-time, so does all physics (in my humble opinion). There exist, if I am correct, no such thing as space-time.
As for space however, I believe that it an aspect of reality that does not emerge from the presence of matter or depends on it. I further speculate that space is as physical as matter. That is is as dynamical as matter (but not in the sense that is understood by GR).
On that, I congratulate you on a well written and interesting essay. I will certainly go back to it myself.