In 2021, BMW will begin using a new vehicle platform that integrates combustion and electric powertrains on the same production lines. The first electric Bimmer to emerge on the platform will likely be the BMW i4, based on the iVision Dynamic concept shown here.
You might think of it as an all-electric version of the BMW 4-Series Gran Coupé, perhaps slightly raised to make room for a battery pack under the cabin. Preliminary specs indicate the i4 will be slightly shorter and wider than the Tesla Model 3. It will have a driving range of more than 300 miles. A cheaper, shorter-range version will follow.