Lifeblood of company in SQL
If the lifeblood and guts of your company are in an Oracle database, you need to make damned sure that everything works perfectly before moving to ANY other database. Unfortunately, very few enterprises probably adhere to sound development practices like strict separation of database manipulation logic from presentation, so you can't just replace the back end. And a lot of Oracle databases are legacy ones and the designers and developers are long gone, leaving few traces of documentation behind.
Oracle will be a tough nut to crack and replace. Now, if somebody came up with a mapping layer to transform SQL calls into whatever NoSQL uses (not even sure if feasible), and with performance comparable to Oracle, then Oracle and Larry would be sailing around in deep doo-doo.
Biting the hand that feeds IT
