We can approach classical behavior from the quantum mechanical formulism via the application of the Ehrenfest theorem [1] in limiting situations (e.g. as per the article, cases where "the wave function is highly concentrated around a point").
I suspect you are instead referring to unification of general relativity with quantum mechanics, which has indeed not yet been accomplished. (However, it's worth noting that quantum mechanics has been found to be consistent with special relativity, and the union of the two yields much of modern particle physics).
