If energy density were to double, so say the type A battery went from storing 25 kWh to 50 kWh, then that just means that the type A cars can go twice as far. It's still the same form factor. Serial numbers or other identification and tracking could be used to charge the customer appropriately. If you're looking for something specific, the swap app could tell you who has what in stock. As the 25 kWh batteries wear out, they're replaced with 50 kWh batteries.
I'm tempted to get some for my MAGAt in laws, but I don't want to support the camp, and I don't think the in laws would get the point - they're probably in support of the camp.
eVoLuTiOn is just a ThEoRy!