Its not likely they'll ever become common place in the pet trade, not as long as health departments and the CDC consider them a public health risk nation wide in the US and Canada. The permits to be able to just rehab them legally are not easy to get. The hassle involved if you did get caught with one doesn't extend to just the health department freaking out - but it can easily end up with fines, or even potentially, criminal charges if they think that you put anyone else at risk.
The CDC actually almost lifted its control on the possession/importation exotic bat species a couple of years ago when they were redoing the laws and then suddenly realized what that would mean and decided to keep it under their belt.
Bat care isn't really much more involved than most herp care - just a different set of rules to go by.