This is why, if Louis XVI died in an accident of some sort, hunting or otherwise, then the realm would fall under a regency for Louis XVII. Now depending on if it was one regent or a whole council then you'd have someone(s) else deciding France's fate. While I think the Absolutist system would have imploded sooner or later, it could have been ended more peacefully.
The Regent would either be Marie Antoinette by tradition or the Comte de Provence as the next senior Prince. The Queen Mother's popularity wouldn't have anything to do with her appointment as Regent. But if she fails it would definitely go to Provence. While Provence later became firmly constitutionalist (I'd never really consider him liberal) as Louis XVIII, I'm not sure what he was like politically during the 1780s.