Bing Maps features are currently powered by Navteq's mapping services anyway, which is owned by Nokia, so it shouldn't be that hard to merge the backend with Nokia Maps, which are more comprehensive, useable, and offer a greater variety of additional services than Bing Maps in its current state.
CEO Stephen Elop confirmed the upcoming Nokia branding for Microsoft's Bing map service in an interview, saying:
In the time ahead, what you will see is, across all the Microsoft properties including Bing maps, more and more work will be done by Nokia. We did that for important reasons as we had the better mapping assets so it made sense. But it also creates some balance in the relationship with Microsoft.
So when time passes, we will start to see the Nokia brand pop up out of the box on Windows Phone handsets from manufacturers as varied as Samsung, which also makes WP devices, and RIM, which uses Microsoft's Bing search and mapping technology, as per last year's agreement.