I ride 20 miles a day in Minneapolis on my e-bike. My biggest fear is when we will ruin it for everyone. There just isn't the proper infrastructure for them. Bike paths around here have 10mph speed limit signs and are mostly mixed use. Not enough connecting roads have bike lanes. It will grow wildly popular once a cheap US based lithium battery supplier appears (Tesla/Panasonic).
I don't see a lot of people who aren't already comfortable cycling to work (though maybe preferring to get there faster and with less sweat), going out and buying an e-bike.