Apparently the Great Hall has/had an official name: Ticket Lobby.
Not sure what you'd envision for the hall, except of course not the dated design of kiosks along north and south.
The north side is set to be retail/commercial, presumably a long restaurant. VIA has dibs, if I understand correctly, to both sets of kiosks running along the south wall, but obviously needs only one set at this time.
Recall:
Hmm, seems broken; how about:
https://en.m.wikipedia.org/wiki/File:Prince_of_Wales_at_the_official_opening_of_Union_Station.jpg