THIS IS a good idea. Excellent idea really. It would require stations that could change the battery out jack spratt and on the dime. People aren't going to wait more than about 2 minutes to swap the battery. It can be done. However, you'd have to have one or a very few standard size batteries. One size for small and medium size cars and one for trucks and larger cars. It could be done though. Interesting idea. Obviously you would pay a charge for the replacement battery. The cost of electricity to charge the battery would be part of the price as well as the cost of labor to keep up with them all the time not to mention buying the batteries. There would have to be a national battery exchange program as it is unlikely that only one company or service station system across the country would handle them.
The people handling these batteries would have to be licensed and certified for such. You don't want just any DA rolling batteries around. And you want to make sure they know how to connect the batteries correctly and not drop them, etc. One DOWN side I see with this is that it would not likely be a self service installation! You would almost be going back to the model of the full service station to have an attendant "fill up" with a recharged battery.
Each station would have the business of keeping up with them. Testing, replacing, inventory, ordering, moving, transporting, distributing, warehousing, etc all of which are pretty well understood. For that matter the stations would be in a good position to deal with the recycling of worn out batteries so that they don't wind up in the bottom of a landfill one day. I could see a business in this. Just don't expect the oil industry to jump right on board! :)
There is one fact about this though. It is still not as cheap or as convenient as filling up your own gas tank and jumping back in the car. If they could find a way to do that then maybe. But I don't trust people to be honest with self service battery replacement. Not to plug it in right and to deal with moving batteries, damaged batteries, defective batteries, etc. People that pay a full price for a battery but then the station didn't know it was defective and an argument ensues at the next station over a refund and yet the battery didn't come from the same company that owned the station that installed it last time. Talk about a SERVICE nightmare. Some way would have to be created to deal with his problem. We live in a sea of DA's. :)