I will let somebody far braver than me analyze whether the economy of France "collapsed".

But I can in part answer the question about being fed. Potatoes which had been pushed as an inexpensive and nutritious food source for decades by various rulers suddenly became popular in continental Europe at the end of the 18th century. Potatoes are an amazing food source because they are resilient to temperature fluctuations and weather events. The also grow quickly and don't require a skilled workforce to harvest and process. Perhaps best of all an army marching over a potato field will not crush the potatoes making them unusable. The potato is definitely not the complete answer but it did have a significant impact on feeding the massive armies of the French Revolution and also feeding the industrial revolution of the 19th century.