There is lately a debate about whether a new generation of even more powerful particle accelerators would be scientifically warranted. I have said a few times that the LHC's most important discovery may be, not just confirmation of the Higgs boson's existence, but determination of its mass as being around 125 GeV, because that places the standard model vacuum on the edge of instability.
Light scalars have a finetuning problem, and the theoretical expectation was that there are other particles (such as superpartners) that render physics "natural" through quantum cancellations. The failure of such particles to appear, along with the discovery that the Higgs mass is tuned to a critical value, might lead one to suppose that whatever mechanism is responsible for this critical tuning, is also responsible for stabilizing it.
As it happens, the Higgs mass was more or less predicted by Shaposhnikov and Wetterich in 2009, using an alternative quantum gravity paradigm. Even given the attractions of string theory, I always thought their work was mysteriously neglected. But now it occurs to me: maybe it's because their theory is premised on a 'desert' - no new particles to discover at higher energies - so it has no instrumental value when making the case for new colliders.
