It was announced that a new Phone Companion app within Windows 10 will be able to connect PCs to mobile-devices, regardless of the OS people are using. This is what Redmond said:
That’s why we’re announcing a ‘Phone Companion’ app built-in to Windows 10, which will help you connect your Windows PC to whatever phone you own– whether it’s a Windows phone, Android phone, or iPhone.
This is where Microsoft will have a leg up over Apple, as the iOS company has a Continuity feature, which is similar to the Phone Companion option, but the Continuity feature only works with other Apple products.
Microsoft formally announced a Cortana app for Android and iOS:
Today, we’re announcing a Cortana application for Android phones and for iPhones which works as a companion to Cortana on your Windows 10 PC. The ‘Phone Companion’ app on the PC will help you install the Cortana app from the Google Play or Apple App Store onto your phone so you’ll be able to take the intelligence of Cortana with you, wherever you go.
The Android version of Cortana is going to be available “at the end of June,” according to Microsoft, and the iPhone version won’t be available until “later this year.” Cortana can also be found in Microsoft’s Edge browser.
Google previously said that they aren’t concerned about Cortana, since it isn’t going to have the same level of device integration that Google Voice search and Google Now do.