I believe there is a plan to build a station before the airport spur
That the Woodbine Station and already behind schedule being built to replace Etobicoke North Station.
At the same time, can't add the 4th track to match the 401/409 tunnels until Etobicoke North Station is remove or a change to match the track in place for the industrial track. Doing that has a safety issue for the current pedestrians crossing.
Then there are the stations doors that were build for the DMU if they will match the bi-level doors spacing, but not floor heights.
Given the timeframe that the DMU's were to be EMU's and where we are today, are 2 different things with an unknown date when it will happen. Maybe ML will have to find some use locomotives that would be able to run on the elevated line if none of the exist fleet can do the job until the line is electrify. Not my field for motor power and weight ratio to the elevated line.
This is what you get for rushing a project and not using the correct equipment from day one. A lot of I told you so are laughing over this mess. Going after the Pan Am games has really bit the rear of everyone.