Would Edmonton be willing to do that? Granted, it's not impossible, but I do wonder if Leduc even wants the LRT to come to their city, let alone all the costs to build it all the way out there.
And also regarding the YEG connection, unless city expansion goes all the way there, there's nothing to stop at for 10 km between the airport and Desrochers/Allard. The only way it's worthwhile is perhaps have an exclusive line going directly to the airport that goes at higher speeds, which solves the 80 km/h speed limit problem and any delays having to do multiple stops.