Sean Carroll has some good talks on this. Basically there's two frontiers: intensity and sensitivity. With intensity going past LHC is looking very difficult b

Sean Carroll has some good talks on this. Basically there's two frontiers: intensity and sensitivity. With intensity going past LHC is looking very difficult but not necessarily impossible. There's been advances in compact linear accelerators that look promising. With sensitivity we're got a lot of untapped potential to observe high energy particles/physics produced by nature. I don't mean to trivialize the difficulties but there's reasons to be optimistic about us learning new physics in the coming decades.