Putting the lines underground in downtown is going to be a small miracle and really tough. One of the benefits of the downtowns of cities in the west is back lanes - power lines all end up there (for the most part). Unfortunately, when Halifax and all of HRM was planned we didn't go with lanes, until after the explosion for the hydrostone.
Personally, one of the things I would love to see done in a new greenfield community is to develop a lane type home, which could be on a very narrow lot. We see a lot of them here in Calgary in the inner city communities, where all the lots typically have backlanes and so people split them into 25' lots and build narrow but deep homes with detached garages off the lane. Yes, you can still have a backyard!

But putting the lines underground in downtown will be tough...they'd likely end up under sidewalks and so if work is needed, up comes the sidewalk.