That's what most of us will be doing in the years to come, changing our jobs every two-three years or so. It's hard to predict beforehand which job positions will be in excess in 3 years and which ones will be in high demand. I mean, it's similar to sports betting: if a team will win most likely( read: a job will be in high demand) then many people bet on it (read: many people learn that job) and your reward becomes close to nothing. Some contemporary thinkers say that bioengineering is a very promising specialization. But then again, if everybody knows that, we can end up with excess of bioengineers pretty soon.