Room to grow housing and office space requires a whole lot of development to happen. My greater point is that there is very little incentive for most people to move to Detroit compared to other locales that are further along on actually having a lot of the type of housing that is popular on the west coast, some semblance of working public transport and infrastructure, etc. The M-1 Rail is a good start, but I think we are still years from Detroit being a truly viable choice.
There are better options than Detroit for this largely just because Detroit is very far behind other cities that can offer some of these needs now and grow into the future ones. Detroit is still at the stage of needing to grow a bit more to support the influx.