I think one thing that can help bring back the revenue is that, of course, in a lot of the rural areas you do see post offices that basically have been put down to almost nothing except for just a building there, which could be easily used for the postal bank. That would be saving money on the actual building of a bank just for Canada Post.
As for training and software, I'm pretty sure there are a lot of local communities that have a lot of high-tech guys whose main focus is on computers and software and who work in low-income areas and rural areas. I have met quite a few of them in my travels. They could easily be trained to help Canada Post workers learn the basics of how to work the software and training. Whatever the set interest rate is, people would come to the banks to use them.
If I remember correctly, I know when I was a kid I didn't see this, but it was pointed out by many people who were a few years older than I was that there used to be some kind of banking already, back in the day.