I want to start off the response by saying I do not have any places in Slave Lake, nor am I looking at any. Frankly, too far away for me.
That being said, I have thought the same question. I have come to the conclusion that I don't have an answer. There's so many variables.
Some people who lost their homes will likely not return. However, I would think it's fairly safe to say that the majority of the homes will be rebuilt. Even those formerly belonging to those who don't return have lots with developed services pretty much place. There's also the major town commercial buildings to replace including several government offices. This will result in a boom that will require lots of housing. I would imagine the government may relax requirements for temp housing. I wouldn't be surprised to see a new mobile home park or two spring up. All these forces will pull different housing in different directions, no idea where things will land. Certainly, while emotionally the town will never be the same, the economic effects of a tragedy like this are typically relatively short lived, and I imagine in the longer term (5-10 years out) there won't be much in the way of change, other than an unusual amount of newer buildings.