For those still skeptic about the whole swapping viability, if I just look at myself as a customer, I'd love to swap my 60kWh pack for an 85kWh pack at a nearby service station before going on a long road trip. It would mean I can skip some of the Supercharger stations and get to my destination faster. Glad to pay a rental fee for this service.
If I had a 40kWh pack, the benefit would be even greater since I won't even be able to do road trips with that pack.
Now, assume for a moment that 40kWh pack will become available with GenIII and by that time, there may be a 120kWh pack option. This means low entry price for the GenIII, being able to make long road trips for a small fee, skipping perhaps two or three SC stations, and not overburden the SC network.