Microsoft is working on a new format for the UWP Universal Windows Platform. Not all apps may be universal even if they are in the Windows store.
This is going to change the way that apps are made for Windows, this is going to break a lot of legacy apps and Windows 32-bit and 64-bit apps. This is going to change how Windows works to bring the same apps for Windows 10 to Windows 10 Mobile etc.
What it means to you, the customer is that you won’t be able to run legacy apps, but you can run these new UWP apps on different Windows platforms.