At the last possible second last night I mailed my remaining Rakghoul DNA to someone else before the servers went down for the patch. What happened to that DNA and any remaining in player's inventories, cargo holds, etc.? Was it removed completely? If it remains, is it sellable/tradeable or otherwise usable now? The patch notes didn't mention anything about the event at all.
All the extra DNA in mail and inventories was kept.
The plague was not removed; I was still infected when I logged in. Further, I was able to explode and infect others, and I received the normal 5 DNA for doing so. (Edit: It is no longer possible to infect other players.) The DNA and the companion customizations do not appear to have changed in any way and can't be sold. Jeelvic is no longer in the game (or at least not near the Stardream) and I haven't seen any more Rakghouls on Tatooine.
The "Rakghoul Resurgence" recurring event has brought back the Rakghoul DNA, and old saved DNA works and can be spent at the event vendor while the event is active.