ok so lets see if i understand this right: if you enter a ETA into the Flight Managment System the aircraft when under control by autopilot and auto throttle will adjust the thrust settings and flight profile to meet the set deadline?
and no this probaly means airliners will still be delayed.
With the really advanced airplanes, it's possible, but it's generally not done.
Generally you just tell it where to go. If you have an advanced aircraft you can tell it what speed you want as well as altitudes and speeds to cross various fixes at.
Aircraft like the CRJ I'm on the FMS controls LNAV only, the VNAV information is provides is advisory only (still spoils you, it tells you what rate of descent to descent to cross the fix at an altitude as well as what angle of descent that gives you. It even puts a little marker on your VSI showing said rate of descent).
Modern large airliners have auto throttles, which is the bit thing you need to allow the FMS to control your climbs, descents, and speeds.
These days, if ATC wants to change your arrival time at a fix, they usually just assign you a speed to maintain.
