As a user who can, has, and does use Bitcoin for 'speculation and profiteering', criminalization would suck.  For someone who is already a criminal the suckage is much less.  Even between these two classes there are areas of overlap.  The set of things I am interested in include, for instance, certain kinds of equipment.  Say, an airplane.  A drug-runner has a different set of interests but an airplane is in many cases one of these.  The upshot is that there will always be this overlap between the black market and the mainstream.  Bitcoin could easily help in this such transactions due to it's historic acceptance and usability.  If not Bitcoin than something else.

In any environment the value of the currency will be largely associated with 'velocity' an 'propensity to hodl' (Satoshi having simplified the currency base part of the equation in the design phase.)  The reality of black markets is such that we are probably at a tiny fraction of where Bitcion _could_ be in fiat denominated terms.  Bitcoin is eminently 'hodleable' and the value flows within black (or simply non-mainstream) markets are huge.