While fingerprint reader support in Windows 10 Mobile was already expected to come soon due to its inclusion on the upcoming HP Elite x3, Microsoft has confirmed it is indeed coming to the platform at large this summer. The confirmation comes courtesy of a WinHec presentation (via Reddit) about planning for this summer's upcoming Windows 10 anniversary update.
As noted in the slide above, Windows Hello will expand to include support for fingerprint readers on mobile with the summer update — a feature that is already supported on desktop. Also noted in the slide is that the integration will work off of the same driver used for PCs, just recompiled for ARM architecture.
As mentioned above, this likely won't come as a surprise to many given the fingerprint sensor-touting HP Elite x3 has already been announced. Still, it's good to see we might start seeing more Windows Phones sporting fingerprint sensors soon.