Ausiello gives us a key detail in the boys' journey to Heaven.

Ausiello gives us a key detail in the boys' journey to Heaven.

Who's going to kill our boys? Lucifer? Random demon? Evil Easter Bunny? We'll just have to wait and see.

Got any Supernatural scoopage? We’re dying out here! —Kristen
Ausiello:
That’s just the segue I was looking for! An upcoming episode will be set in heaven — after Sam and Dean have been murdered!

Source: Ask Ausiello