I think you give too much credit to this polarized mentality. We have to evolve these things, what's easy is generally what's done. Birds didnt built spaceships, they learned to fly.
Our divisive nature is one of simplicity. Take, for instance, power. If i want power, all i have to do is maintain a class structure, which is entirely dependant on the belief that people are not equal. This, in turn, stabilizes the belief that greed and divisivness are permissable states to inhabit.
After that, it's only a short step to loosing respect for humanity outside your ''club'' or class or whatever.
Then, you have the shitstorm we have now, this global ''every man for himself'' principle mixed with people only mobilising to enforce the rules of their specific dogmas.
This is howwe killed the love.
The last thing i want is an end to society, because it is the foundation. Things have to change, but i think the polarized brain is just a part of our makeup, passing through that will make us a more evolved human. But we will still live in the world i have described.
Nothing is the end of everything.
One person can end a Universe.