Rumors point to Google combining their Voice service and their Hangouts instant messaging and video calling service. It's a great move for iOS and Android users, unifying two solid communication apps under one banner, but Google has remained stalwart in not developing native apps for Microsoft's mobile OS.
Google Voice is an advanced voicemail and texting service. Google issues a number, and users add their own personal numbers to the service to route calls. Say you have Home, Work, and Cell numbers. Those can all be collected under one Google Voice number, and each incoming call can be routed to the phones you want.
Third party Windows Phone developers took it upon themselves to fill in some of those Google gaps with apps like MetroTalk, but Google will be pulling the plug on those pipelines this month. With no word on a Hangouts app for Windows Phone, it leaves users in the lurch if they've been relying on Voice as their main phone number.
It's an odd move as Google is a services company and profits off of advertising. Microsoft has been making some significant inroads with entry level smartphones thanks to their relationship with Nokia. This demographic is one Google has been trying to crack into recently as the premier smartphone market is starting to mature. If Google were to offer some of their services like Hangouts and Maps on Windows Phone, they'd still be able to monetize users who aren't investing in the Android ecosystem.
If you're using Google Voice on Windows Phone, hit the related video to see how you can continue getting texts and calls.