In a lot of places it has. I can't even remember the last time I opened anything in Office. At work people share links to google docs instead of sending docs.
IMHO, people still send the docs or portable files especially when they have to share final and binding contracts. There is quite a bit of lifecycle of a document after it has been created on Google Docs!
I am always fascinated by people sharing corporate documents on Google Docs... It blows my mind to put that in the cloud, than allow people to share if among themselves, so if any of them gets his/her account hacked, the hacker will have access to company's corporate secrets... And that's without assuming that Google has access to those as well.
From experience, the global Oil & Gas industry is completely reliant on Excel, and that will not change any time soon. They use it for nearly everything... It's the common UI to bigger, complex systems, and it's the data storage/manipulation tool for more specialized, or "simpler" needs.
Many of the non-Excel applications in this space started out and grew from a monster Excel workbook.