@nokiadeveloper just tweeted that Stephen Elop noted in a session for the developer community at Nokia World said that Qt will be 'primary vehicle' to reach people all over the world.
Not to reach "the next billion" alone, but people all over the world. For me, this includes smartphones to the same extent as the new feature phones. Smartphones would be the Symbian phones, also the ones still to come, the N9, but most of all also Windows Phone, as this is the primary smartphone platform for Nokia in the future. Mango doesn't have a Qt port, and probably never will have.
But as Niklas Savander said Mango on Nokia is just the beginning, as Mango was pretty finished when Nokia jumped on board. In Apollo, Nokia will have way more to say about Windows Phone development, so there still is the possibility for Qt being included in Windows Phone. Microsoft wants it to succeed. And I think Microsoft needs Nokia for a real success of Windows Phone. So Nokia should have a pretty good position for negotiations here.
And who knows, maybe there will be another Qt flagship after the N9?