If you want a nightmare check India xD
The real irony is that we talk about the Egyptian Air Force and its diversity and the Indian Air Force and its diversity and how that leads to complications and extra cost... the whole purpose of the F-35 was to reduce the different types of fighter aircraft deployed in NATO... simplification and standardisation to make things cheaper and simpler... and lets be honest... that has not really worked out very well either.
Having an all Flanker fleet or an all Fulcrum fleet for Russia would reduce performance in some areas and not really make many huge savings at all...
In theory there are savings to be made in simplifications and unifications of roles to one aircraft, but if that aircraft is faulty and has hundreds of unresolved flaws it can actually make things worse and much more expensive too.
Careful what you wish for.
Perhaps Russia should develop a stealthy subsonic cruise missile they can sell to Egypt... it will make those MiGs more valuable to them and more capable.