(Originally answered in quora)
How? I can tell you how it won't be like, but it'd sure be fun if it's any close: http://b.cregox.com/a-novel
One thing is for certain: humans and humanity will be completely changed by it. A bigger evolutional leap than anything that ever happened before.
And it will most certainly happen before 2040, as Ray Kurzweil genius predicts.
I truly cheer for start seeing it within the next 7 years (5 years before a PC can emulate a human brain on its own), but who knows? In science, any prediction with more than 5 years advance is about the same as saying "nobody knows, we can only hope".