Not sure exactly what Portland's plans are, but Minneapolis is planning multiple ~15km lines. I suppose they may put the streetcars in right of ways outside the core, but it's hard to say.
I realize the situation with, for example, Queen St., isn't ideal, but at the same time you can't argue that it doesn't work. Regardless of the flaws, ridership on existing long streetcar lines is very high, and they make an enormous positive impact on the city.
From personal experience riding the Queen streetcar the problem with keeping streetcars running smoothly comes mostly from the dense, busy central areas like Queen and Spadina.
Considering the number of people walking and taking TTC in the core, vs driving, the logical thing would be to reduce the space available to automobiles by 25% or more, for example, by creating pedestrian malls/transit corridors on King or Queen. The idea seems shocking and revolutionary in this city but you will find such things in Melbourne and Portland (sure these are small cities with more spread out population and space to spare) but also Amsterdam (which is a big city, has narrow streets, density, and an extensive surface transit system).