How will Sam and Dean come back?

If Supernatural does ever come back, of which I am hopeful. How do you think with the boys now in Heaven will they work around this one. In The Winchesters we have already seen Dean back on earth and Jack coming to collecting him and bring him back. So the boys will never be alive again as we new them. How do you think the writers will get around this one? Yes, they are a creative bunch and am expecting something like, I wasn't expecting that....

So share your thoughts.....