When is LOB segment too large?

I inherited a database that has a table used to store binary documents in a BLOB column. This table has become a big dumping ground for documents generated for the business. To date, the tablespace is 4TB in size and the only thing in this tablespace is the table with the BLOB column. So the 4TB tablespace is almost entirely one very large LOB segment. The table has many millions of rows of data.
As I write this, there are no issues with the table this large and its very large LOB segment. But I am planning for the future. My long-term goal is to partition this table and put one year's worth of documents in their own tablespace. But my company has not licensed Oracle Partitioning yet and before we do license it, I want to provide some justification for the database option. Which bring me to my questions.