I've compiled a list of features and changes that would move the game forward
1-Make sure when we set a flight for all year service that it stays forever.
2-Make sure that a save is compatible whith every update. restarting every update could depreive the game from any excitement.
3-Airport development: building terminals is good but building bigger terminals is better, also building a bigger terminal should affect the airport capacity going from small to medium for example. bring back dealing with aiport officials features from v1: asking for customs office (requirements), asking for a bigger runway...etc
4-Give us the possibility to demolish airline facilities when we don't need them.
5-Give us a go back to main menu/reload options
6-Let the demand be dynamic and proportional with the amount of traffic that goes through the airport.
7-Make it a bit easier to make a profit
8- Make it so aircraft lose health overtime (maybe even have some crashes that affect the reputation and the finances)
9- Give the possibility to convert old aircraft to cargo
10-Give us some flight configuration presets