According to Seat 61, most of SNCF's remaining domestic Intercites de Nuit will be dropped at the end of June. The three remaining will be the trains to from Paris to Briancon, Rodez, and Latour de Carol, as those are considered "socially necessary" due to the destinations having no easy alternative route by high-speed train or air travel.
France is so small that I don't 'get' overnight trains within the country. We once traveled from Florence to Paris overnight; once was enough.
It seems that low-cost airlines and high-speed trains are replacing the overnight trains. I never liked overnight trains, anyway, and more than once had to change trains in the middle of the night, or arrived at a train station at 4am.
Oh, well, everything changes.