Thanks for the link. I'm not even saying GR isn't emergent from something else. All I'm saying is that it contains the sum total of what is currently the proven mathematics governing gravity.
I myself have many 'unproven' things about Physics, that I believe, with a high degree of probability (near certainty). Dig thru my past posts for lots of them. For example, I believe Minkowski Space is indeed itself emergent. I think our entire universe exists on the "surface" of a 3D Event Horizon (manifold). I don't believe in the Big Bang, because our reality 'formed' not from a singularity (exploding out), but like a Black Hole (falling in). So I'm open to lots of ideas, but just pointing out the what we currently know as General Relativity, isn't even that complex, and is just about a shape (curvature/tensor) at every point in spacetime. It's all we've "proven".