A machine is at the mercy of its creator, but so are we. We have the ability to shut the mind off, we have the ability to "turn off" a human, and even screw with our "programming".
At the current time of technology no we cannot replicate the Brains capabilities, but in due time we will be able to replicate and eventually surpass the ability of the brain. We've already made robots that are capable of learning (there was a robot that didn't know how to balance/walk, they gave it some time with a learning algorithm and sure enough in due time it learned to walk more efficiently than the robot that was Programmed to walk right away). This is a perfect example of how to approach this technology, they have to let robots learn things themselves. To program them to do ALL tasks would take many years and would be buggy, so now they are working to approach things with learning algorithms.
Yes at the moment they are ALL limited to poor programming, but in the many years to come we will come up with more. another thing to really check out is Quantum computing - this will really boost the ability for machines to become more intelligent.
If you think about it, soon enough all it'll take is a small program. Let the machine go and it'll come back in no time with loads of information, capable of holding coverstations, etc. You grab that information and impliment it onto future machines, and repeat this process.
we will never hit a wall with this technology, lot of people think the wall is the programming but even today we're finding new ways. in 30 years we may have walking talking robots, in 50 years self replicating robots capable of doing almost all jobs. in 100 years Robots may be a race all on their own.
Maybe not, but the fact is humans want to replicate AI perfectly, and we will continue for many years to do this... And if our history has proved that we will achieve this.
I for one am looking forward to having a robotic companion to assist and hold good conversations.