Charles de Gaulle life extension and carrier continuity

What could justify extending Charles de Gaulle beyond covering delays and retaining carrier skills?

Those reasons are already sufficient because France wants to avoid a gap in carrier capability.

Covering successor delays and retaining carrier skills are considered sufficient reasons to extend Charles de Gaulle's service. Avoiding a break in French carrier capability is the central justification. Other nations' experience of allowing such gaps supplies the caution behind it.