So another mod removed this because it violates our rule against what-if questions, but I think it's interesting, so I'll answer it informally.

There wasn't much of a chance of this. I mean, it's hard to say (which is why we don't allow these questions in the first place), but it just doesn't quite fit. There wasn't a long-standing military establishment in Israel--in the early years, the military was essentially illegal militias under a new name. Moreover, this situation meant that the political leadership had directed the paramilitaries in the pre-state era, so the political and military establishments weren't separate enough for one to fight the other. Not only that, but the military was formed largely out of the Haganah, which was the armed wing of the faction that held political power in Israel after the elections, so there was little reason for the military to object to the political leadership.

The biggest test of this would've been when Israel accepted the reparations agreement from West Germany, which led to massive protests and rioting, which included Menachem Begin (sort of) calling for a coup. But the military still defended parliament against the rioters. And why shouldn't they have? The old-guard of sorts was from the military of the political party that was currently in power. The right wing's old militia was dismantled. The military didn't have the political independence to make military rule a possibility.

You could also ask about the risk of becoming a one-party state. After all, Labor was the dominant party for 30 straight years (first as Mapai, then as Alignment). But the Israeli political system made that impractical, too. Even though Labor was firmly in control of parliament, they weren't able to go it alone--except for a few months as the result of a party merger, Labor never held a majority of seats--they generally had around 45 seats of 120. The government was in constantly in coalition with other parties. And these coalitions were not composed of just a few parties, but a broad array of parties, representing diverse groups. The first knesset, for instance, had a government formed by Labor in coalition with a religious party, a Middle Eastern Jewry party, an Arab party, and another left-wing party. Any attempt at a policy to put Labor in a more powerful position could've easily alienated one of the other parties, causing the government to collapse and new elections called.

tl;dr the origin of Israel's military, being the armed wing of the political group in power, meant that the military would have little reason to take power. the political system ensured that the dominant political party couldn't make things a one-party state