UK in France getting French Nationality - wifes art 10 card?

More Brexit problems. I'm a British citizen living in France(15 years) now with my non-EU (Thai) wife and step-son.
My wife wants me to apply French nationality rather than permanent residency, even though we are currently think of moving to another EU country - we will keep French house anyway.

My family currently have five year article 10 residence cards which expire August next year, but have been here for more than the required 5 years for an article 20 (permanent residency) card as they had 2 one year cards first.

What would happen to them if I get French nationality ? Would their art 10 cards become invalid? Would they have to reapply under the more stringent French immigration system? Would the situation change after they get art 20 cards?

I suspect it will take me till after they renew their cards anyway, but I don't want to mess things up unnecessarily.