Even with a bare majority, I’m pretty sure the AMLO alliance can peel a few scant seats from PRI and PRD after-the-fact. Also considering that there’s more to lose with the various coalition possibilities on the anti-AMLO bloc, I’d say AMLO is actually safe till the election after this one, but the focus now is enacting reforms to make him popular again and change Mexico with it.
One of the things that most interests me is with the PRI. The longer they aren’t in power and end up aligning with PAN, the looser their grip is on the few institutions and reliable voter bases they have left. Depending on how long AMLO remains President, he could do quite a bit of shaking with the bureaucracy and military that were previously staffed with loyal PRIistas.
I can't imagine that he'd seek re-election, trampling the massive precedent set by the Mexican Revolution. Especially someone like him who has made Mexican history such a centerpiece of his image.