Let's say the infrastructure is there for this, and you don't have to purchase the battery with a new EV...you just purchase a battery plan for like 100$ a month. It'd easily cut 10-20k off the cost of an EV up front.
Plus, quick charging isn't quick. At best you're looking at a 20 minute stop, and you're praying a stall is open when you get there. This could solve that problem as well.
It's an interesting idea.