The Germans will struggle with this. They do things very well, but they are rigidly procedural and so it takes them a long time to make a major change. 2018/2021 would not surprise me in the least.
A long range electric car is more challenging than a hybrid or short range electric because you can't simply re-purpose an existing platform. To get long range, the only logical location for the large battery in in the floor. Once you do that, the entire structure of the car has to be redesigned from scratch - and that means new EVERYTHING. That's a major undertaking.
I think you're going have competing 400 km range electrics out of Ford & GM far sooner than out of Germany. The US auto companies certainly have their flaws but they react faster. I bet we'll see something by model year 2017. Of course, Tesla will be a couple of steps ahead by then.
It's astounding that Tesla was able to do this from scratch so quickly with minimal resources. And meanwhile the big manufacturers with the big bucks are still stumbling around in circles.
It reminds me of that scene from Ironman, where Obadiah is grabbing one of his researchers by the throat, hollering "TONY STARK MADE THIS IN A CAVE!". And the researcher glumly responds "I'm not Tony Stark!". Okay... a bit of an exaggeration, but even so the parallel is there.