My own humble opinion, I think the best way to bring Gibbs back to NCIS is the story he's never told anyone... until now. I wonder if something bad is going to happen to Lala and she vanishes without a trace. And Gibbs blames himself for not protecting her because he ignored a gut feeling that something was wrong. Then after all these years, his old MCRT unearths a lead that's enough to bring Gibbs back to the Navy Yard from Alaska and bring "the story of her" to a fitting conclusion.