What would his reputation be like if he had died of a stroke or heart attack before 1940, given he was already elderly??? I am no expert, but I imagine he was pretty conservative by his time's standards already.
A great one, you will see a lot of timeline about him playing a big role during the war.
He was a great man loved by the right wing for his exploit and by the left because he was republican the good majority of high general in this period were monarchist.