Windows 10 Cloud will only allow users to run Universal Windows Platform (UWP) apps from the Windows Store. The dialog states that “This version [Windows 10 Cloud] was made to help protect you and your device by exclusively running Windows Store apps” which, once again, confirms that the SKU will only allow users to run apps from the Windows Store:
As this is just an early version of Windows 10 Cloud, I don’t think it would be ideal to claim that Windows 10 Cloud won’t allow users to run Win32 apps that were downloaded from the Windows Store. It’s possible Microsoft will allow this to happen in the near-future, but we’ll have to wait and see until Microsoft officially releases this new version of Windows 10.
Windows 10 Cloud could be a very interesting version of Windows, to be honest. Windows 10 Cloud seems like Microsoft’s second take on Windows RT, which didn’t really succeed due to the Windows Store not having a lot of useful and powerful apps back then. In the case of the new Windows Store and the Universal Windows Platform, the story isn’t much different either — consumers, especially power users, would still want to be able to run the classic Win32 apps on their PC — even if they are from the Windows Store.