Basically your reasoning reveal that without the Plank's constant (i.e., if we put it to zero) we loose the absolute scale of the universe and what remains is a scale invariant classcal word where elemetary particles can be small as we want. But this is not. Elementary particles exist and the quantum Comption length fix a scale: the dimension above which the world becomes quantum. So a world with a null Plank's constant is contrddictory and out of reality. And then the question arises again..... what kind of classical mechanics we have? one possible solution is: we have to renounce to the deterministic classical mechanics (it does not exists but it is just an approximated model) while in our world we have the stochastic classical mechanics where fluctuations are unavoidable. Even small change, phylosophycally speakng it is a great jump: we have to renounce to our presumptin of total free will (that would desced by the deterministic classical mechancis) and accept a time horizont bejond which we cannot go.

Thanks Jon, I could never think that.

If you start from the Heisenberg's equation of motion for a general quantum mechanical operator and calculate dp/dt, while evaluation K.E. will commute with momentum and in the commutator of the potential term, namely [V, p] Planck's constant will factor out which cancels with the Planck's constant in the denominator. Therefore, now the equation of motion for the operator becomes dp/dt = negative gradient of V. Taking expectation value of p, you will recover Newton's second law. In such a treatment there is no need to take Planck's constant to be zero while recovering a classical limit.