Reading the case details on the halifax.ca website -
http://www.halifax.ca/planning/Case18270Details.html - the following statement seems somewhat misleading:
There are various municipally registered heritage buildings in the area including the Garden Crest Apartment which directly abuts the subject property and is also a provincially registered heritage property.
However, looking at the Bing Maps Bird's Eye view there is already a highrise between the Garden Crest Apartment at 1544 Summer Street and the new 20 storey proposal. I took a screen capture which illustrates this below. It is also noteworthy that only the facade of the Garden Crest Apartment building is original (
http://www.halifaxhistory.ca/GardenCrest.htm).
This looks like a very desirable location. So I think that if it gets approved there is a good chance of it being built in the near future.