Microsoft increased capacity 40-fold earlier this year when it bumped the humble 25 GB of storage for OneDrive for Business accounts up to 1 TB, then a mere four months later it increased it again - this time infinitely to unlimited storage. OneDrive capacity has grown by leaps and bounds this year.
Microsoft is upgrading Office 365 customers to unlimited OneDrive storage, but that doesn't mean you can just put all of your files in the cloud.