The other difficult part in long games is fleet transitions. While a majority of players never succeed to survive the expansion phase, a clear majority of the survivors is then trapped because the fleet transition has not been properly planned.
The fact that other players jump on the most popular models adds to the difficulty. If A320 is there in 1985, and you plan to replace your B727 fleet by A320s, and the model is launched while you sleep, and you wake up and connect there is no free production slot until 1994, well, you're in bad position. I can afford to wait up to the mid 90s, so I'm quiet.