I would like to see the ability to add shuttles to different terminals (e.g in Orlando international) but this could implement different research options e.g one per line then allow the trains to change sides allowing for more trains per line and more capacity and maybe different trains with different capacity’s
or maybe the player could add a bus route from terminal 1 to terminal 4 as it could have more busses and be cheaper to build but not to fuel and maintain
also as a side note I would like to see those flat escalator things (the moving floor thing) which will increase the speed of people making them not miss their flight