[bausson]

But what if said manufacturer decide your car is not 'supported' anymore?

You may not even be allowed to turn to alternative battery suppliers, because it might be forbidden by contract. Their are some user protection laws in some countries (say, France), but it won't be the case everywhere.

[michaelt]

I was assuming the rental contracts would be long-term enough to guarantee pricing and availability for the life of the car, e.g. a 10 year fixed price contract with the option to renew at the same price for another 10 years.

It's a nascent industry at the moment - I'm not sure how it will play out. Presumably some day battery lives will be proven, manufacturer reputations will be established, and consumers and regulators will know what to look for, check and standardise. Once the technology risks and information asymmetries are reduced, passing the risks to manufacturers will be less appealing and we might all end up paying up front for our 30-year batteries.

[chris_wot]

In Australia, that's called "third line forcing" and is forbidden by law. Surely the U.S. has the same sort of laws?

[girvo]

From my experience, we get looked after well as consumers in Aus, and the US doesn't have near the protection we enjoy. Not sure if that's the case here, but I know it's true on the whole.