If you want an e-bike that will last decades, get a good steel frame bike and put your own kit on it. The reality is that as time progresses batteries will get lighter, cheaper, and last longer. Motors will get stronger and more durable. Even if you can't do repair or upgrade work on your own, as e bikes become more common you can expect repair shops to open dedicated to them. No matter what e bike you get, you will have to replace batteries every 2-4 years (until new tech develops) and thats a pretty good expense. Motors will last longer if taken care of properly. But no e-bike is going to be inexpensive to maintain...but it will be a whole lot cheaper than a car! Btw, one of my bikes is a Bike Friday (handmade steel frame) that is 20 years old and it's just perfect =)