The story of most academic developments is that somebody develops a new technique, then they solve the problems that are easy to solve with the technique. At some point the problems that can be solved with the technique are solved and nobody has an idea of how to break the technique's limitations. Maybe 20 years after that, somebody gets a new idea.

Some examples: perceptrons, symbolic A.I., multilayer perceptrons, renormalization group theory in physics, etc.

It can take 10 years to get a PhD so it is not impossible that the field can burn out before then. I don't believe it is burning out in 2 or 3 years.