The trial is limited to both Audi’s home of Ingolstadt as well as the Zurich area. There’s no mention of how long it will run or how likely it is the pilot will expand.
The strategy is a logical one for companies making deeper commitments to electric vehicles. It’s easier for Audi to sell you on the concept of an EV if it can promise to lower your power bill in the long run. Also, this makes the most of the VW brand’s work on batteries — it can venture beyond selling cars and make sure the batteries it makes find customers. It just so happens that this can both save you some money and, potentially, help the environment in the process.