Looking at the FAQ, there are these items:
21. What is End of Support Life?
This is the end of the product life cycle. Once a product or version reaches its End of Support Life Symantec will stop providing any kind of support services unless Sustaining Support is available for a particular version (see FAQ 20).
22. What is the End of Partial Support?
Symantec sometimes refers to the End of Support Life as the End of Partial Support for those product versions that have a Partial
Support phase. The terms, End of Support Life and End of Partial Support mean the same thing.
So I think it basically means, content stops once we reach EOSL, which for SEP11 is 27th Sept 2014. So yes....time to upgrade...
Thanks