Supernatural's God has changed his mind about why the world needs to be destroyed. When Jensen Ackles, Jared Padalecki and Misha Collins announced the end of Supernatural, there was Shurley only one contender for the final villain. The absentee, egotistical God of Supernatural's world, season 14 revealed that Chuck had been orchestrating the Winchesters' lives from the very beginning. Every tragedy, every trauma, and every shabby motel stay had been written in the pages of Chuck's magnum opus, and for a grand finale, the omnipotent one wanted blood. Specifically, the blood of Sam and Dean as the brothers destroyed each other. Winchesterbowl was, in God's mind, the only fitting way to bring the world to its end.
Only a handful of episodes remain in Supernatural season 15, and the final battle is upon us. Acting on Billie's orders (based on a plan by Adam, of "Adam & Eve" fame), Dean is hoping to use Jack as a God-killing bomb, but Sam and Castiel are searching for another way - one that won't necessitate such a heavy sacrifice. The younger Winchester has also discovered Billie's intention to succeed God when the deed is done, replacing one problem with another. Meanwhile, everything is proceeding exactly as Chuck has foreseen. God maintains that the Jack-o'-bomb will have no effect, especially now he and the Darkness have merged again, making Chuck more powerful than ever before.
However, Supernatural season 15's "Unity" episode doesn't just change Billie's intentions and God's power level, it also shifts God's motivation for destroying the world. Chuck has been steadily collapsing his parallel worlds in preparation for the final apocalypse and, until now, he maintained this was due to boredom. God wanted to end his Winchester story and write something new, but was becoming increasingly frustrated by Sam and Dean's staunch refusal to kill each other. Speaking with Amara in "Unity", Chuck reveals that his true reason for ending the world is frustration. Like a writer looking back over his earliest work, God is ashamed and critical of what he created, believing he could do better by wiping the slate clean and starting afresh. Later in the episode, when the Winchesters once again avoid giving God his perfect ending, the villain effectively gives up on them, accepting that he can't force the brothers against each other but promising to end the world anyway due to his existential apathy for the current universe.
This change to God's motivation tidies up the narrative ahead of Supernatural's final episodes. Until now, God's grudge against the Winchesters has been clear - Chuck's playthings won't behave as he wants them to, and this makes him angry. But God's reason for ending the universe wasn't so explicit - Sam and Dean can't self-destruct if the end of the world gets them first, after all. Now, God's mentality is simplified. The stubbornness of the Winchesters has compounded God's existing frustration at the universe, and the whole shebang has to make way for something better. Supernatural's latest reveal sets up a more straightforward showdown between good and evil, where God has one single goal (the apocalypse) instead of one design for the universe and another for Sam and Dean.
Alas, Supernatural fans will now be wondering whether the long-awaited Winchesterbowl will actually happen. Ever since God stated his desire to corrupt Sam and Dean, fans have been anticipating an almighty clash between the two. "Unity" instead offers a brief scuffle, which may be as heated as Sam and Dean's brotherly relationship gets in Supernatural's final season, turning their attention firmly onto God (and perhaps Billie) for the remaining episodes. With that said, Winchesterbowl can't be ruled out entirely. God revealed in "Unity" that Sam, Dean, and even Amara were acting exactly as written, and the Winchesters might still be playing to Chuck's tune, while he pretends not to care about their fate. Dean's gunpoint outburst may be the first step towards God getting what the bloodbath he wants, with more elaborate steps on the horizon to ramp up tension between Winchesters.