Hidan´s going to be the ultimate secret counter-weapon of Shikamaru´s all-deciding master plan. You just watch. Something like

Noise from Shikamaru´s backpack: "Mrmrbnmgh!"
Shikamaru: "Shut up, I told you."
The undead and clones arrive
Shikamaru opens his bag and takes Hidan´s head out of it.
Hidan: "You damn-!"
Shikamaru: "I dont have time for this. Listen, you´ll cast your immortality jutsu on the all of the united ninja army!"
Hidan: "LOLFUSRISLYGTFO!"
Shikamaru: "Wanna go back into that pitch black hole, burried alive?"
Hidan: ".... alrighty, damnfucker!"
Hidan uses up the chakra he saved during his long wait beneath the earth.
We see some of Shikamaru´s friend taking lethal hits...but not dying. Once again, Shikamaru, the real hero of the manga, saved the day.