The answer was pretty simple to me - Jack, Kate, Hurley, Sun, Sayid and Aaron. The Oceanic 6 takes Locke back.
I don't think he meant Desmond and Penny though Desmond might decide to go back as well. He would want to help save those left behind even though he
wasn't on flight 815. He still became intertwined with all of them. And Penny would be needed to help get back since she obviously has resources to find
the island. She found it before...
Walt might go back with them since his dad died there.. sentimental reasons? Oh.. and he's special and might be needed. Maybe the writers want all alive
back at some point before the series ends.
But what Ben said to Jack.. I think he meant O6.
Aaron is not even questionable in my opinion. He needs to go back TO HIS MOTHER.
