I believe that the reason Einstein failed to complete his "Theory of Everything" was because of his rejection of Quantum Mechanics. I believe that Quantum Mechanics in itself is incomplete! I believe that because it is an imperfect thought, Einstein rejected it too quickly. It was repulsive in his perfect way of thinking. I would call Quantum Mechanics the "Theory of Interference". It is really a "key", if you will, that was being offered as a piece of the puzzle that Einstein would need to complete his "Theory of Everything". Having completed his "General Theory", Einstein was repulsed by Quantum Mechanics. Quantum Mechanics is the thought of an infant compared to Einsteins thinking. However, in order to complete Einsteins "Theory of Everything" one has to account for other objects already existing in time and space that would or could interfere with one another. Thus one has to take into account the "Theory of Interference" aka "Quantum Mechanics" in order to write a perfect equation that could be called the "Theory of Everything".
Since Einstein, by rejecting an integral key to his "Theory of Everything", he went all the way around the bush only to find himself going in circles never being able to complete the formula. Objects in time and space effect one another. Therefore that effect/influence must be taken into account via Quantum Mechanics in order to complete a perfect "Theory of Everything". I believe that if Einstein had embraced Quantum Mechanics as only a small piece of the puzzle, he may have been able to complete his "Theory of Everything".
What do you think?