Lets take for example the YikeBike below:
Yikes! Might as well just pin a note to your back saying "I'm a Loser, Please Kick Me!"
And below is a folding bicycle/car with 4 wheels that runs on a combination of gasoline and electricity. So... really its a folding hybrid car with bicycle wheels.
Regardless of what you think of such bicycles (I think they're amusing, but really not worth the expense and the silliness factor) the problem with ALL folding electric bicycles is that they're essentially designed for lazy people who want to get noticed for their gadget. Eventually the kewlness will fade and you will get tired of all the weird looks and having to carry the damn thing to your office or home... or worse, having to deal with battery failure, empty batteries and miscalculating how much distance to go / charge you had left.
I'd argue that if you want a kewl gadget you might as well go all the way and get something like a Carver... which is technically more like a motorcycle... or is it a car? Three-wheeler? I doubt anyone would EVER bore of driving a Carver.
Bicycle purists of course will point out that the Carver runs on gasoline and it has no place on a blog dedicated to bicycles. Have an open mind however and let me point out something...
Electric bicycles get their power from the local electricity grid (unless you happen to have your own solar panel / wind turbine) and thus uses a combination of renewable energy, nuclear and the most frequently used, most hated but cheapest of energy sources... coal. That means your electric bicycle is running off a percentage of coal energy (depending where you live that percentage could be surprisingly high). Furthermore if you are charging your electric bicycle during peak hours (7 AM to 9 PM) you are using a larger percentage of coal because thats when it is needed most.
So its a case of tomato tomatoe. You're not saving the environment by using electricity.
The whole purpose of an electric bicycle is essentially laziness. Its a bit like an electric can opener. Some people can't be bothered to use a hand held can opener and do it the old fashioned way. Or elevators/escalators instead of stairs. Its a lifestyle choice, one people in Western culture frequently take for granted.
I think, and this purely my opinion, this a growing trend towards a broadening market for electric bicycles. Eventually a few major producers will gain popularity and mass production (its the chicken and the egg as to which will come first) and we could see large numbers of people riding electrics in the future... and hopefully by then we will have done away with coal power.
I don't think it will ever replace traditional bicyles however. The added factors of needed exercise, not looking like a dork and saving money (e-bikes cost about the same as a Tata Nano car) will keep this mode of transportation around indefinitely.