Around the current stations on the Sheppard line a forest of condos has arisen, and yet the line still sees abysmally poor ridership. Why? I think that this effect speaks to a fundamental problem with envisioning the Sheppard line as a 401 alternative.
Really, no Sheppard Subway cannot convince people to get off of the 401 that it parallels.
Bang on. A subway is not a valid alternative for the majority of the trips on the 401. The only true competition for highways is GO lines. The stop spacing is just too close together to come anywhere close to highway speeds. The Lakeshore West line acts as an effective reliever for the QEW because the time it takes to get from Burlington (my point of reference, because that's where I am most) to downtown TO isn't that much more by GO than it is using the QEW/Gardiner combo.
Even if the Sheppard Subway went from Port Union to Pearson, it would easily be double or triple the time it would take to travel that same distance using the 401. The Sheppard Subway cannot be, and should not be perceived to be, a reliever for the 401.