In the US, both the federal and state governments are offering some extremely attractive rebates on the Leaf / Volt, so in the end, an end user only has to pay around USD$25k+taxes for a Leaf. A price like that would be extremely attractive to anyone looking for a vehicle in the $20k - $30k range.
IIRC, the Leaf has a decent range (at least 150km per charge, if not quite a bit more), so it'll be a perfect urban car. But at the end of the day, consumer adoption will heavily depend on the vehcile's price.
Electric cars can't just swap out the batteries because there are no standard specifications available at this point. And quite frankly, given the size of battery required and the varying configuration that vehicles come in, I don't see a standardized battery spec becoming available any time soon. As a matter of fact, even with the plug-in hybrids, manufactures are having some issues in agreeing on a common, industry-wide standard, and that's just the plug!
[Moron mode on]
BYD and other Chinese car manufacturers are gonna take over the automotive scene, while GM and the US empire will go bankrupt!
BYD is a battery manufacturer. If they agree to exchange a worn out battry every 10 years. it will be a big selling point for their cars and environment friendly/responsible at the same time.