It reminds me of a similar regulation we had here from '90 to '93. You got around 1500 euros price reduction on a modern car if you scrapped an old one, and you didn't have to pay road tax on it for 5 years. As there were a lot of '60s R4 alive back then, this regulation wiped them away... :-( . Good news were that some of the better cars, not only R4s, were not scrapped actually but sold as parts donors through a series of auctions. Very few people back then were forward-thinking and saved some really rare classics.
I think that R4s in danger in France now are those 80s ones that are used as everyday workhorses. Earlier ones are considered to be classics by many people now.