I'm thinking about buying my first e-bike. I see that e-bike batteries are brand-specific and will stop charging after a few years' use. If a manufacturer goes bust or changes designs, won't an e-bike become junk after that point if there are no new batteries of that type available?

Yes, you have a very good point. It is particularly an issue with small niche players with 'advanced' designs. Relatively OK with Bosch as it has such large market share, and a reasonable history of supplying spares (but often at very high price).

There is an alternative, which is to go for bikes that use generic Chinese parts. Even if you can't get an exact replacement after a few years you should be able to make some slight modifications and keep it going. These bikes are mostly much cheaper to buy, and much cheaper for spares. However, you need to be competent to work on any issues yourself (with the help for forums such as this); it is quite likely your LBS won't touch such a bike.

One reason some of us buy generic system operated bikes or build our own that can easily be converted by use of 3rd party generic batteries or controller systems.

Branded mid drive torque sensing bikes I would never entertain one.

In the end it boils down to ones skills and ability.

6 hours ago, ThisWreckage said:

I'm thinking about buying my first e-bike. I see that e-bike batteries are brand-specific and will stop charging after a few years' use. If a manufacturer goes bust or changes designs, won't an e-bike become junk after that point if there are no new batteries of that type available?

My bike's been going for 12 years. It's brilliant. It will be landfill one day after the worms have eaten my flesh. If you stick with standard Chinese stuff, your ebike can last forever.