The TTC's last plan to extend the Bloor-Danforth line west was born during the Peterson era I believe, continued on the radar during the Rae Days, but was dropped like everything except Sheppard during the Dark Ages.
That plan had the line running along the north side the CP tracks, diving underground to avoid the back of some places of business, with a potential station at the East Mall, then curving south to Sherway for a station at Queensway and the West Mall, and then curving west for a terminal station at Dixie at the GO line.
The owners of Sherway Gardens at the time had pledged (as far as I remember) somewhere around $25 million to help bring the subway their way, and were planning on extending the mall to the northwest corner of the property to meet the new station. A bus terminal was planned for under the hydro corridor immediately west of the West Mall. Since that time a large complex of condos called One Sherway has been approved, and its first towers are now under construction. Land was also identified at Evans Avenue and the West Mall as a Toronto gateway, namely to take commuter parking for those driving into town on the QEW.
Sherway's bus ridership is not low because nobody goes to Sherway, it's low because it's such a slow route from Kipling. With direct subway access, one could imagine similar traffic to that which uses Yorkdale station on the Spadina line, and yes doady, there is a lot of it: (the Spadina line is not quite the disaster you make out in your post).
I believe that the East Mall station was not seen as a high priority because it was assumed that most Mississauga buses would meet the new line at Dixie, and that the TTC's East Mall bus might be needed to serve Dundas Street as far as Kipling once other TTC Dundas bus service was replaced by the subway extension. Nowadays, I could see some special bus-only ramps being built to connect Hwy 427 express bus services to a station at the East Mall.
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