We can set a required time at a waypoint already, (Airbus). I sometimes use this feature to make sure I reach the first waypoint of an oceanic crossing at the estimated time we have given, and I have in the past used it to avoid infringing night curfews etc. It would be good if ATC would give us required arrival times to point x at our destination airport and this would help everyone save fuel by slowing down if necessary and avoiding vectoring for spacing, but I don't think we would need +/-10 secs?