What we need is someone that can look at a map and strong arm the railways.
We have a wide set of tracks that are directly beside the Gardiner at Strachan that go all the way to the DVP! Build a new Gardiner from Strachan above the railway tracks (can be a tunnel for the tracks OR an elevated roadway) all the way to the DVP. Might be some minor issues at Union and a couple of bridges to deal with but these can be worked out, but we will have to stop the new fancy stuff they are planning at track level there (union).
Problem solved, cheapest possible solution. Ralway will have major issue with anyone doing this but the federal, provincial, and municipal governments need to grow some and set them straight for the better good of the country.
That's one of the busiest rail lines in north america. Closing the gardiner would have a much smaller impact on the canadian economy.
My vote for the best solution is one side at a time, alternate traffic direction on the other side (i.e. in the morning EB only on the gardiner, WB only in the evening). It would still cause a traffic disaster, but at this point, I think that is unavoidable.