Assuming SuperCharging will be available with the lower priced Model 3, it would seem there would be future scale/congestion issues at SC stations? Is there a market for those who own/rent/live in condos, apartments etc where charging over night is and likely will never be an option? It might seem strategically placed Swap stations located in high density populations (e.g. Santa Monica, San Francisco, etc) would appeal to those who would like an EV, but don't want to spend hours a week 'charging' up. Subscription Packs (4/30 announcement)?
When there is a line of cars waiting at Supercharging Stations there will be a market for Battery Swapping stations regardless of where the owners live. Obviously it is about convenience and the value of peoples' time.
If I owned a Tesla and I lived in a multi-unit dwelling (MUD) that didn't have accommodations for charging I would be forced to find alternatives to overnight charging. The first thing I would do is see where the closest Supercharger Station was. If it was a reasonably distance that's where I would go. If it turned out it was congested and IF it also had a Battery Swapping Station collocated there I would pay the fee for the swap. However, if it was congested and didn't have a Battery Swapping Station I certainly wouldn't drive the typical distance between Supercharger Stations just to do Battery Swap.
Tesla started the Supercharger network for the most part with an emphasis of installing Superchargers BETWEEN destinations. They are just beginning to address the needs of owners in cities and have started to install Urban Superchargers. In my opinion the first Battery Swapping Stations should be installed where there is demonstrated congestion at a Supercharger Station. If that Supercharger is in an Urban location, then it may be of use to people with Teslas that live in MUDs without overnight charging. As the realtors say, location, location, location.
It should be noted that 30% of the US population live in MUDs. That's a large percentage to write-off for EV ownership. Ironically in Florida those cities and counties with the highest EV adoption rates also have a high incidence of MUDs. In Fort Lauderdale, where Tesla sells a lot of Model Ss, 57% of the population live in MUDs. As you suggest, there might be a need for Battery Swapping Stations in such locations, but first there needs to be Urban Superchargers.
Another issue facing those folks who wish to substitute regular Battery Swapping for home overnight charging is the shear wear and tear on the car. After Tesla gets a bit of experience under its belt I wouldn't be surprised to hear them make an announcement regarding the maximum recommended frequency of Battery Swaps.
Larry