If civil war breaks out, the US will have to get involved. Problem is that Russia and China would sell (or give) weapons to AMLO and get in bed with him.
I don't think Mexico is enough of a prize to rate the risk the Chicoms or the Ruskies would run to interfere.
But Chavez and Castro and a few other super Lefties could become more than a small problem.
I just don't see it coming to that. It will be interesting to see if Fox mobilizes the Federales to open the Zacalo.
I was there just 2 months ago and they had the usual Socialists there DEMANDING Free Housing, etc.