I'm gonna go out on a limb and say that claims of a possible shortage are FUCKING BULLSHIT being used to keep people scared.

Remember those 39 millions hospital masks?

There are plenty of dosages in-hand and in the pipeline:

In response, Novartis has pledged a global donation of up to 130 million hydroxychloroquine tablets, pending regulatory approvals for COVID-19. Mylan is ramping up production at its West Virginia Facility with enough supplies to make 50 million tablets. Teva is donating 16 million tablets to hospitals around the U.S. On Friday afternoon, Amneal pledged to make 20 million tablets by mid-April.

IF an actual shortage arises -- and this will not happen -- but IF it did that would be the time to start prohibiting prophylactic use. To do so now only abolishes hope, instills panic, and actually assists with the spread.