A few thoughts.
Most of the Dead Sea Scrolls were written on parchment (animal skin), not papyrus (crushed reed). A jar containing papyrus documents would be unusual, but entirely possible. A reed mat was also found in Cave 10. Just to be difficult, I wonder if we can rule out the possibility that the jar held another reed mat.
The jar lid is unprovenanced. John Allegro bought it. He concluded that it was from a Qumran cave, but not from one of the eleven that we already knew held scrolls. Could be. But I would keep an open mind about its provenance.
As Professor Taylor says in a comment to the DQCAAS article, this find doesn't necessarily imply that more scrolls remain. Just that some once did, but they are now decayed and gone.
For hope of finding more scrolls (possibly very early ones) see here and links. It seems unlikely. But I am an optimist.
Cross-file under Ancient Material Culture and Techology Watch.
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