Perhaps. I'm not sold on that, however. When one looks at all the ill-conceived mutterings Obama has made since Jan. 2009, it's a possibility, IMO.
That's the last thing they need - it would be much cheaper in the long run to find another sheriff who can be bribed.
Judging by the number of assassinations, including those of government officials, in Mexico over the past year or two, I'd have to say their methods don't follow your logic. To a analytical mind, you'd be right. But that's not how they operate. They're scum, and act it out.
In Mexico it makes sense - they have more money and resources than any Mexican state government and they have a chance at controlling the situation politically as well.
Taking on the US government brings it to an entirely different level.
While this President may be a ditherer, if they act they would be guaranteeing that the next President wouldn't be.
The fate of Pablo Escobar should be instructive.