Since this is an area I'm very familiar with, I'll throw in a little science about why these predictions are not only realistic, but actually probably a bit pessimistic.
First of all, our understanding of the human brain has improved vastly in the past two decades. Especially in the areas that will be necessary for creating intelligent machines. The cortex (the part that kind of looks like a round blob of small intestines, with all the creases and folds) is much like a computer with a bunch of processors. Previously focus had been paid to the individual neurons as the processors. But a much larger unit of processing is now becoming the central area of focus; The
Cortical Minicolumn which, in groups for a
Cortical Hypercolumn. As minicolumns consist of 80-250 (more or less, depending on region) neurons and there are about 1/100th of them compared to neurons, it cuts down on complexity significantly.
Numenta and others are starting to take this approach in simulating cortex. Cortex is largely responsible for "thinking". The other parts of the brain can be seen, to some degree, as peripheral units that plug into the "thinking" part of the brain. For example, the hippocampus is a peripheral that's associated with the creation and recall of long term memories. The memories themselves, however, are stored in the cortex. We have various components that provide input, many of which send relays through the thalamus which takes these inputs of various types and converts them into a type of pattern that's more appropriate for the cortex and then relays those inputs to the cortex.
The cortex itself is basically a huge area of cortical minicolumns and hypercolumns connected in both a recurrent and hierarchical manner. The different levels of the hierarchy provide higher levels of association and abstraction until you get to the top of the hierarchy which would be areas of the prefrontal cortex.
What's amazing about the cortex is it's just a general computing machine and it's very adaptable. To give an example (I'd link the paper, but I can't seem to find it right now and this is from memory, so my details may be a bit sketchy, but overall the idea is accurate), the optic nerve of a cat was disconnected from the visual cortex at birth and connected to the part of the brain that's normally the auditory cortex. The cat was able to see. It took time and it certainly had vision deficits. But it was able to see, even though the input was going to the completely wrong part of the brain.
This is important for several reasons, but the most important aspect is that the brain is very flexible and very adaptable to inputs. It can learn to use things you plug into it. That means that you very likely don't have to create a very exact replica of a human brain to get human level intelligence. You simply need a fairly model of the hierarchical organization and a good simulation of the computations performed by cortical columns. A lot of study is going into these areas now.
It's not a matter of if. This stuff is right around the corner. I will see the first sentient computer in my lifetime. I have absolutely no doubt about it. Now here's where things get really interesting, though... The first sentient computers will likely run a bit slower than real-time and eventually they'll catch up to real time. But think 10 years after that (and how computing speed continually increases). Imagine a group of 100 brains operating at 100x real time, working together to solve problems for us. Why would they work for us? We control their reward system. They'll do what we want because we're the ones that decide what they "enjoy." So 1 year passes in our life, but for them, 100 years have passed. They could be given the task of designing better, smarter, and faster brains than themselves. In very little time (relatively speaking), the brains that will be produced will be vastly beyond our comprehension. Imagine what they can do for us.
I know it sounds very science fiction-ish, but it's not. It's the future. I've never been so sure of anything in my life and it's why I spend a great deal of my free time studying neuroscience, neural simulations and AI.