That’s right, resurrection isn’t going to work in Season 15 (I’ve lost count of how many times Dean and Sam have died and come back).
So, Sam and Dean will not only have to deal with zombies, Heaven and Hell, but there’s also the very real component of death and the emotional impact it will have on the Winchesters.
Additionally, co-showrunner Andrew Dabb has said that the Winchester brothers will lose certain characters in a very “real way,” indicating that deaths will be permanent.