The research following up on the Em-Drive. I believe that they will make it practical once they figure out they need to use a tesla coil to fill the resonator with high frequency tesla electron radiation.

Not an easy jump out of the gravity well still, but it means that a nuclear reactor with closed thermal/turbine circuit can be made, and it means a very powerful space probe that can get a lot further away and still send back signals to us, and that it could be sending us much closer images of nearby stars than we have ever seen, maybe even fling one into orbit of Sirius or Proxima Centauri within a few decades.