It’s worth bearing in mind the new aircraft coming in, like the Rafale, are not like-for-like or one-for-one replacements, but instead are qualitatively better as MadRat says, as they are multi-role.

For example, in a strike mission, the Rafales are self-escorting and can more than look after themselves unlike, say the Jaguars…..they can also be used in other roles such as air-to-ground (not just at stand-off ranges)….or even as part of the nuclear triad like the Mirage-2000s.

Older aircraft being replaced, say like MiG-21s, simply do not have that versatile capability. Even if squadron numbers are kept the same as now (as older aircraft retire), their replacements are so much more potent.