A British politician said that, "A week is a long time in politics," and 1748 to 1789 is over half a century. Having said that if the history of France was close enough to OTL for the Revolution and rise of Napoleon to still happen, would France still have lost the Napoleonic Wars?
I think France would have still lost because the it conquered and absorbed the Austrian Netherlands into France almost immediately and they lost. The French might be even more successful in the early stages because they have larger standing armed forces and the starting line is further north, but in the long term they still don't have the resources to win.