There is a strong disincentive to not fly older planes for 60 years. Maintenance costs on 25+ year old planes are huuuuge.
For fleets, depends what sort of stuff you're flying. You can fly DC-6/CV-340 for pretty much everything to start, then the convairs turn into better turboprops (fokker, HSwhatevernumber, etc). DC-6 turn into DC-8/707/Vickers for a bit more size and more range. The tupolev could be a good LH plane too, except that the production line is very, very slow, so extremely tough to get enough of them. Not a big fan of comet/lockheed/etc early jets, they're incredibly thirsty and don't offer much benefit in terms of range, seats, etc. Rather use things like the AWsomeothernumber.
Personally, if I manage to win the f5 battle for a new JA space, I'm planning on boycotting all douglas/airbus/boeing products, and seeing how things go. Efficiency be damned! The only issue with that will be LH, as there's really nothing in later years. L1011 is okish, but once you're past that, the only LH plane is the IL-96.
Does anyone know if Moscow - Vnukovo gets transferred to Sheremetyevo when it opens?