It is not feasible for VIA Rail to run trains on every piece of track in Canada, so we need to prioritize.
I have said this before, but there is a strong argument to create a rail corridor in Alberta. Unfortunately with the Alberta government agreeing to support the construction of a hyperloop between Calgary and Edmonton (please discuss that project in the
Hyperloops in Canada thread, and if you want my opinion on it, see
this post). As a result, I don't see any government putting any money into conventional rail in Alberta until that project runs its course.
Outside of Alberta and the Eastern Corridor, the largest city without rail service is Victoria (pop. 367,770). There are talks about bringing back the E&N, but we will have to see where that goes as the track needs significant repair.
IMHO, the rail project outside of the either Alberta or the Eastern Corridor that has the most merit, is upgrading/relocating the BNSF track to Vancouver used by Amtrak Cascades. That is going to be a tough sell though, because both Amtrak and BNSF are American railroads, so it is harder to justify to a Canadian government. It also isn't VIA Rail, so is out of scope for this thread. The rail bridge over the Fraser River also needs to be replaced. It is also used by VIA, so it might easier to swallow; however, finding a good solution won't be easy because of the elevation and river traffic.