I understand that currently the population at about 350,000 (incl. Queanbeyan) is a little small to justify it, but from my observation, a city of about 500,000+ seems to be line where these sort of systems become practical. Given Canberra is only 150,000 short of that number, the equivalent of finishing Gungahlin and Molonglo Valley towns, as well as starting construction on a new town at Kowen Forest as is slated.
Given the rate at which these towns seem to be getting built (about 30years each) that would mean that around 2040 Canberra would likely have grown to around 500,000 people and support thus some network of this type.
I suppose the other factor to consider that given Canberreans love the city form for what it is currently and don't want excessive sprawl or increased building density, then increasingly Canberra as a city will become reliant on the region for housing. This can already be seen in terms of people commuting from Yass, Goulburn and even as far as Cooma. I have heard the odd call (generally from the Business Chamber) to introduce a 4 train per day (2 morning peak, 2 evening peak) from/to Goulburn.
So sorry for a slightly long question, but I think there's a lot to be set out. Basically if we take 2050 as a date to have a decent network running by, is it feasible, what sort of network would it be and where would it serve?