From my ignorant perch, this looks like an attempted revolution, headed by a rock-hard Leninist revolutionary who will stop at nothing. It may not matter if their public support dwindles. If they have enough willpower and the forces of democracy don't, they can win. I think you may be too optimistic.
Mexico is far too advanced a country for them to win. But that does not mean they cannot cause significant trouble, because in some ways, they are already doing that. And it could get much worse, especially in light of the near chaos in Oaxaca and a steadily destabilizing situation in Chiapas.