Macron says they’ll rebuild in 10 years. It took about 100 originally.
https://abcnews.go.com/Internationa...ld-notre-dame-fire-destroys/story?id=62424888
I also read that a historical society recently digitized most of the structure and it's construction, so assuming they stick with the original 'plans' - they're in a way better position to reconstruct faithfully.
They've also already amassed some 1 billion in Euros for the reconstruction.