The whole profitability question is basically meaningless. I remember those days of "profitable" routes as well. 31 Greenwood, 77 Spadina, 92 Woodbine South and 511 Bathurst. All made back their costs and then some based on their ridership. However, you'll notice something in common about all four: they're short routes.
The TTC's accounting seemed to take in only the number of riders each route took, applied a value amount for the fare, and then divided it against the cost of operating each route. All short routes had an advantage over long routes.
Which is to be expected, in some ways, since people using such a short route are taking short trips, even to the subway, and any bus or streetcar that has to travel farther to serve the same number of people increases costs without decreasing revenue.
But it's sort of silly to think of these particular routes in that way, since most of those riders weren't using just these routes to get to and from where they wanted to go. These services were feeding into other services, and the TTC decided to change the accounting of various routes to reflect this better.
The fact is, public transit across Toronto as a whole is unprofitable -- just like every other service across North America since the Second World War. We still carry loads of people, however, but we are unable to overcome the fact that carrying people comes at a cost, and we're unable to build ourselves (yet) to be dense enough so that the average trip lengths drop and the revenues outpace that cost.
People say, "the subway is profitable, let's cut the unprofitable routes", but how many people would still be taking the subway if the thousands of people who travel on the unprofitable routes no longer had those routes available to access the subway? The same is true about the so called profitable surface routes: if you remove the other routes that these profitable routes connected to, there would be fewer reasons for passengers to take those routes.
It's pretty obvious that, under the old accounting system, 510 Spadina would be a profitable streetcar route, but it would still be a meaningless statistic.
...James