Gabriel Aul, the head of the Windows Insider program at Microsoft, stated that the OneDrive cloud storage service "'is being integrated directly" into Windows 10, rather than being offered as a stand alone app.
Aul's response came from a question on his Twitter account, with a person asking him why OneDrive has not yet become a universal app. His reply?
What does this mean, and how will it impact Windows 10 users? At the moment, we don't have any information on how OneDrive will be integrated into Windows 10 and how this will affect its features and updates. It's possible that its integration will be something like Skype, which replaced Messenger in Windows 8.1. It's still a Modern app but it's also a deep part of the OS.