> not everyone has access to charging infra at destinations

So there is a big chance you won't have access to battery swapping station also, since it would require even more powerful infrastructure. If there is no electricity there will be no battery swapping station. Or maybe you just want to buy multiple batteries and carry them with you?

> swappable batteries would also radically lower vehicle and battery fabrication costs

How so? Well, maybe if cars were sold without batteries that would of course make sense, but then you'd pay for the batteries anyway at swapping stations. I'd say that it would increase the overall cost, since you'd need more batteries than cars to make sure there is always one waiting for you at the station. But that's just guess game now.

> what happens when the battery’s lifespan is breached and capacity craters.

You go to the mechanic and replace the battery, like any other part of a car that goes faulty :).

Right now, most EV car consumers have access to charging infrastructure and are not doing very long trips all the time. Those who do, just buy petrol cars simply because they are much more convenient for those uses. If the market of home-charged electric cars saturates, then it's time to compete with ICE cars on those long distances. We are not there yet. And we may never get there, who knows? I know that if I were to buy a new car now, I'd go for electric regardless if I could swap my battery or not. It's just that they are expensive now due to high demand.