Windows 10 really could change everything for Microsoft.

Greg Sullivan, Microsoft’s Windows Phone Director of Public Relations, had this to say: “We expect many will upgrade.” How many? 1.5 billion. That’s how many Windows users exist worldwide.

Windows 10 will work across all devices, from phones to desktop PCs and everything in between. Windows 10 will have universal apps that will work across all these devices.

That means 1.5 billion users will be looking for apps. that work on all platforms.