Crows are amazing creatures, but they lack the advantage of hands, and I think that really matters in the long run. If something is going to take our place, they probably need to be adept tool users, so the same issue is there for Elephants, plus they lack the ability to rapidly adapt to new environments and food sources. Maybe Octopodes will make a surprise "come from underwater" victory though, who knows?

I'm glad that I'm not the only one who thinks about this kind of thing by the way.