Hi,
I had the same idea that gravity could be an emergent phenomema from entropy, however it looks like it may have been disproven by measuring the gravitational force on a neutron. A possible alternate theory is that gravity, mass and spacetime curvature can be explained by viewing mass as spacetime curvature, and antimatter should have an opposite spacetime curvature to matter. Gravity would be emergent in the sense that it is a result of the spacetime curvature aka matter.
cheers, Jamie