Will we ever successfully complete a brain transplant?
I would predict it would be possible in the future, how long i cannot say. 200 years ago some of the technology we are using today would have been impossible to their comprehension.
People never believed man would land on the moon, people never believed you be 2000km away from someone and make a video call. The list is numerous of events we never thought were possible to the human race.
All we need is the right technology, with it almost anything is possbile.