A lot of screaming.

In all seriousness … I think we’d see Sam and Bowman become even more protective of the little guy, trying to keep him shielded from the world that’s waaaay too big for him. Jacob, in the meantime, might go into adrenaline overdose or something, as that kind of scale gets really mind-boggling and terrifying.

There wouldn’t be any safe interaction with Dean anymore at all, and that would be sad. :c