Raising the retirement age is a pretty stupid solution, for a good reason: raising the retirement age is the standard solution when there are too many elder people compared to younger people due lack of births in the past 20 years.
French system isn't in crisis due lack of births, there are enough young people to pay elders' retirement.
The problem is due lack of jobs, and so in such situation raising the retirement age is not going to work because you basically keep more expensive elder people while keeping cheaper younger people unemployed.