Microsoft will soon release a similar feature as already used by google spreadsheets. Excel users will share a file from OneDrive or SharePoint Online. This will allow multiple users to work on a document the same time.
How to use this feature:
- Be an Office 365 subscriber and opted into the Fast level of the Office Insider program
- Have Version 8017.1000 or later installed
- Save your file to SharePoint Online, OneDrive or OneDrive for Business.
- Work with another user who is on a co-auth enabled platform
- Share your file with others.
There is currently no official release date. Read more on this topic here.