Im new here so i figured i share a little theory (?)
as his "immortality curse" stated that it can be lifted if all the Ten Commandments are killed, so what if all of the members of the Ten Commandments died and as stated meliodas is over 3000 years old will meliodas die by his old age? Or his curse will just be lifted and making him not immortal anymore thus he can now die. An interview with the creator of the seven deadly sins said they'll be 3 story arcs consisting of 300 chapters cause each story arc consist of 100 chapters... As i told earlier what if meliodas' curse as been lifted and died because of his old age?, that'll be a happy ending for meliodas stating "his dream is to remove his curse" but for us, we will basically die cause of feels.. This has ben on my head for awhile now