This is my main concern with E-Bikes. I think they are a great invention, but the way they are being developed is just with obsolescence built in.
-Each manufacturer has its own battery standard and fitment, which changes every couple of years.
-the motor is in theory replaceable, but economically uninteresting comparing with getting a new bike
-any self repairs, battery reconditioning, non official maintenance is heavily discouraged, losing warranty cover or even official support
-because the motor allows it, the relative slender early models are now replaced by heavy machines closer to a motorbike than a bicycle. You won't go far if the motor or the battery gives up and you need to pedal on your own steam
-E-Bike Kits, that would allow to upcycle many existing bikes, are only available as DIY solutions. That means only a minority can benefit from them, and your have no support in your local LBS if something goes wrong
I live in Germany, one of the early adopters of E-Bikes. The first wave of E-Bikes is now flooding the used market. The crappy ones (initially sold in supermarkets, hardware stores...) are unsellable and destined to the (electronic) scrap. The ones from reputable brands are sold only after extreme discounting, as you might have to account for an extra 500€ for a new battery.
I expect a law in the near future to deal with all this waste, but it'll come already too late.