Halifax Transit's planning has become a lot more ambitious lately. A couple of years ago the plan was to tweak things over a 15-year period and now council is looking at overhauling the system with new BRT routes, ferries, and electric buses by 2030. They found that back in 2017, 89% of bus service could already have been electrified, and it looks like it's not very expensive to switch fleet renewal over to electrics (moderately capital cost, moderately lower maintenance and fuel costs).
Here's the BRT and ferry network map, which I think is pretty similar to what they had a few months ago:
A bit of discussion:
https://morethanbuses.ca/2020/05/25/brt-electric-buses/
This would be a big deal for the city since there are so many routes that are served by a large number of loud and dirty diesel buses. Halifax is in an awkward position where it needs lots of transit and has bad traffic but doesn't have clear corridors for building rail. And I wonder what the point is of building electrified lines right now if battery-powered vehicles are already viable and will be even better in 10-15 years.
The Green Line specifically is interesting because it's a growing corridor on the peninsula. There's a lot of active development and potential along that corridor.
A drawback of this plan is it still has relatively weak intermodal connections. For example it doesn't connect up with the South End train station (which doesn't even appear on the map; there's also a transit bus to the airport that terminates at Scotia Square), and the ferry terminals aren't major bus terminals. I'm not sure it would be practical to fix that without more expensive underground infrastructure.