You can have a Blackbird but you will also need;
a tanker to refuel 10 mins after take-off because it guzzles fuel at low altitudes
4 state of the art graphics cards and a block of ice, if the console can't render an Adder at 200 mph how will it handle a Habu doing Mach 3?
A much longer runway than anything on the map now, the Titan uses 2/3's of the Zancudo runway
and entire maintenance squad per bird, and even then it will be down about 100 hours for every one it flies.
but I'm sure R* will only have one guy with an SMG guarding it so you can jump the fence and steal one whenever you want