I think Entropic Gravity is looking very promising.
Verlinde claims that it is starting to make some sense of the Dark Matter and Dark Energy problem.
This theory could change a whole lot of things in physics. And might provide a way to finally bring Quantum Theory and Relativity together.
General Relativity actually adopted equations that would be consistent with Newtonian Gravity without deriving it from first principles.
And probably that is the problem with its current formulation. The Entropic Gravity might provide the deriviation and mechanism for it.