Welp, looks like that whole General Relativity vs. Quantum Mechanics thing has been put to rest, once and for all: read
An Exceptionally Simple Theory of Everything, and be illuminated:
All fields of the standard model and gravity are unified as an E8 principal bundle connection. A non-compact real form of the E8 Lie algebra has G2 and F4 subalgebras which break down to strong su(3), electroweak su(2) x u(1), gravitational so(3,1), the frame-Higgs, and three generations of fermions related by triality. The interactions and dynamics of these 1-form and Grassmann valued parts of an E8 superconnection are described by the curvature and action over a four dimensional base manifold.Well, duh. It's so obvious now.
