80% of the many zetabtyes of data on the Internet will soon be unstructured. Of the remaining 20% of structured data, only a fraction of it would even qualify as relational.
Other structured data could be simple key-value stores, tabular row-and-column stores (single table, no joins), and even graph data models. Like, an Excel spreadsheet is "structured." But it's not a SQL RDBMS.
All of which are basically "NoSQL" though you can shove it in an RDBMS if you want. Just as you can slurp an Excel spreadsheet into a RDBMS. Still doesn't make Excel "relational" per se.
Can you cite a source that shows the opposite to be true?
I don't have $4,500 to throw at IDC right now, but their latest in 2021 shows that "structured" data, while still smaller than unstructured data in absolute volumes, is now growing faster than the unstructured data. Basically by tagging it with metadata. (I guess that gives a video "structure?") But this metadata management can be done by use of NoSQL, as is popular within IIoT spaces, or by streaming OOT video providers, not just by throwing all data into an ACID-compliant, locking and blocking transactional RDBMS.
