There's also a good possibility that one of the high ranking military officers will use the opportunity that will arise from the chaos to orchestrate a coup and put themselves in power.

That is, admittedly, a possibility I hadn't considered.

This treaty has been active for 50 years, what would Israel gain from destroying it?

If the treaty remains active then makes sense, but I doubt anyone will care about a peace treaty with a failed state. You know how when a country just falls apart its neighbors go after the pieces? That's the sort of scenario I'm envisioning here. Admittedly my thinking might be overly simplistic, and I should've considered more orderly possibilities, but at least in the Syria-style absolute chaos situation I'm imagining (which after thinking about it isn't as likely as I thought) of I don't see why they'd honor the sovereignty of a state that ceased to exist, in the same way nobody really cares about Syria as a sovereign state anymore.