  By analysing probabilistic foundations of quantum theory we understood that
the so called quantum calculus of probabilities (including Born's rule) is not
the main distinguishing feature of "quantum". This calculus is just a special
variant of a contextual probabilistic calculus. In particular, we analysed the
EPR-Bohm-Bell approach by using contextual probabilistic models (e.g., the
frequency von Mises model). It is demonstrated that the EPR-Bohm-Bell
consideration are not so much about "quantum", but they are merely about
contextual. Our conjecture is that the "fundamental quantum element" is the
Schr\"odinger evolution describing the very special dependence of probabilities
on contexts. The main quantum mystery is neither the probability calculus in a
Hilbert space nor the nonncommutative (Heisenberg) representation of physical
observables, but the Schr\"odinger evolution of contextual probabilities.
