Sorry, in Spanish only (use google Translate).
I think it's a good idea. Not just from a practical point of view, but also cultural. The treaty that banned coca chewing was signed over 50 years ago. And while I have not read it, I'm almost sure it did not include chewing tobacco. This was a trully colonial imperalialist measure (and I never use those terms). I say that because it obviously is a treaty that is Euro-centric in it's scope. The vast majority of the items banned are those of ''indigenous'' cultures but very few western growths were banned.
While I don't support lifting a ban on all the substances, it's been proven that chewing coca does not lead to any nefarious behavior or health issues anymore than tobacco does.
It is almost certain the United States will lead to an objection of the measure proposed by Bolivia, which would halt any immediate lifting of coca chewing as illegal, as then the appropriate authorities would have to review both requests. If no one did object by January 31st, the measure put forth by Bolivia would become legal.
I hope Brazil and Argentina back Bolivia on this. Coca leaves is part of High Andes culture whether people like it or not, just as much as tobacco is part of western culture. And as long as no proof is given the chewing natural coca is dangerous to society, I support lifting it's restrictions. If the USA wants to be known as a culturally intolerant government, then they will go ahead trying to stop it.
If other societies abuse the plant, it's not the fault of Bolivian or Andean culture. Of course, any mass trafficking of coca leaves that are obviously intended for refining should remain completely illegal and Bolivia and others should agree to fight that with redoubled efforts.