re: A marvelous idea for electric vehicles
I don't think consumers would go for it, although on the face of it, it's a good idea. Battery packs are large and massive items, and I can't believe the labor costs wouldn't outweigh the time saved in charging.
On the other hand, having the packs easily removable and replacable would facilitate putting a more efficient battery into your older car if you wanted to "trade up." One thing that irritates me about some modern electronics (some Apple stuff) is the "sealed in" battery.