Steven Weinberg was visiting CERN recently and gave a talk entitled The Quantum Theory of Fields: Effective or Fundamental? He discussed the ups and downs of the “market price” of quantum field theory, showing a decline since a peak in 1984, followed by a conjectured increase in the future. He also described the history of his work that led to the modern point of view on the role of QFT as an effective theory.
He ended with comments on the “asymptotic safety” approach to quantum gravity, noting that it is quite possible that string theory is not needed, that the world can just be described at a fundamental level by quantum field theory (and thus his conjecture that QFT may come back into fashion as a fundamental theory):
I don’t want to discourage string theorists, but there’s just the possibility that maybe that isn’t the way the world is, that the world is much more like we’ve always known, that is, the Standard Model and General Relativity.
Update: Weinberg has a new paper on the arXiv, covering much the same material as this talk.