A French Succession War in 1744?

While reading about the Dauphin Louis, the son of Louis XV, I found this piece:

"From an early age Louis took a great interest in the military arts. He was bitterly disappointed when his father would not permit him to join the 1744 campaign in the War of the Austrian Succession. When his father became deathly ill with fever at Metz, Louis disobeyed orders and went to his bedside. This rash action, which could have resulted in the deaths of both Louis and his father, resulted in a permanent change in the relations between father and son. Up to this point Louis XV had doted on his son, but henceforth the relationship was more distant. He was very close to his three oldest sisters."

It happened in August 1744. If the fears of Louis XV had happened, and both father and son had died from a contagious disease, what would happen?

As Philip V had renounced his and his descendent's rights to the French crown, the legal heir should be Louis, Duke of Orleans. However, as Philip V was completely influenced by his wife, Elisabeth Farnese, could we see him trying to put one of his sons in the throne of France? And how could the death of the king and the dauphin affect the War of Austrian Succession?
 
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