We've now had about 45 years of string theory, and many of the long time practitioners have made big Russian bucks, courtesy of Yuri Milner. What we don't have is what we like to call results. The gold standard in science is prediction - prediction of new and verified physical results. String theory has not been shy about making predictions: supersymmetry, and extra dimensions, for example, but so far neither has made itself known. For now, that leaves String theory in the place where the atomic theory of Democritus sat for 25 centuries or so - tantalyzing but unproven and unprovable.
The LHC was designed to find the Higgs, and it seems to have done that. Nonetheless, many string theorists were convinced that it would produce sparticles - some even bet on it. So far, no go. The LHC is being juiced up a bit, so there is still hope, but the fact is that nobody even has a clue what the energies are at which supersymmetry should be found. Unless that can be remedied, it seems unlikely that a next generation particle machine will even be built.
Particle physics might be over for generations.