If they were going to do something bold, they could rebuild the cathedral in a Gothic Revival style as it's not really big or impressive enough for the main cathedral of a metropolitan city of 2.6 million. However, I'd prefer a new Gothic Revival cathedral somewhere else, perhaps on a grand new public square. Alas, religion has declined and we may never see such a project.
As an Anglican myself who attends at least 2 Sundays a month, I've been to many such churches in Toronto and around the world (Manhattan, Bermuda, Anglo Caribbean, Hong Kong, etc). Here in Toronto if you want a big Anglican church go to St. Paul's on Bloor St. It's huge, by far the largest Anglican church in Canada. It's not hurting for funding, and recently completed a fantastic reno. The Toronto Star's Christmas Wish choir concert takes place at St. Paul's each November and IIRC fills the place the capacity (well over 2,000, IIRC). My own church is a much smaller affair, which I prefer
http://www.stpetercarlton.ca/
In New York City the Anglican (Episcopalian) churches are centrally run and funded. This means that the finances of all the churches are pooled together and then dolled out as needed. This is a far more successful model than the Canadian version, where each church property is a separate corporation, where it succeeds or fails on its own financial capabilities. The problem with this model is that churches in poorer areas, where one may argue a church is most needed or can do the most good mission work, financially fail and close, while churches in wealthy areas, like St. Paul's Bloor St. are bringing in vast surpluses of cash. As for St. Bart's in Regent Park, they've got other challenges, but I assume the Diocese is given them some time to attract new residents to the pews before deciding anything. The building is not heritage designated, IIRC. The Slavic church across the way is ugly, and I often wish it would be bought and added to the park beside the new pool.
Back to Toronto, it is the United Church of Canada that is really struggling, and closing many of their churches, while the rest struggle on with mostly blue hairs. Of course one could argue the UCC lost its way when it became the "United Church of Everything" on both domestic and international affairs. But that's another story and OT from Regent Park.