According to The Verge's unnamed sources:
"This floating mechanism would allow Cortana to appear on top of documents, contextually, and provide information and assistance. We're told it's more of a powerful search tool, than an annoying animated character like Clippy. If Microsoft pushes ahead with its Cortana plans then the digital assistant will be able to control even more Windows features, like the ability to mute all incoming notifications quickly."
The report also says that Cortana could be integrated more directly inside Office 365 in future updates and adds that the Action Center in Windows 10 could add more functions as well.
Windows 10 Mobile could also see more Cortana features added in future updates, according to The Verge:
"On the phone side, Microsoft is currently developing an on-tap service for Cortana. Similar to Google Now's feature, Cortana will appear contextually to enable quick access to information or additional search queries."
If this report is accurate, Windows Insider could see these features added in preview versions of Windows 10 and Windows 10 Mobile before they are launched to the general public.
Source: The Verge