Things go round up. Beginning with the standalone option, now you will find OneDrive for Business in every business SKU.
Today Microsoft announced that Office 365 Pro Plus subscribers will also get OneDrive for Business. New subscribers of Office 365 Pro Plus after 12/1/2014 will have it included, all other subscribers of Office 365 Pro Plus will get ODFB with unlimited storage till end of january 2015.
The “Business”-Variants of the Office 365 family: