A Bigger Collider...?

The initial proposal was floated by CERN yesterday.  100 TeV, up from the current LHC's 14 TeV.

The problem is that the LHC was specifically designed to pin down the existence and properties of the Higgs boson, which it did, and which had been predicted decades before, and on which the entire Standard Model hinges.  What's more, there was a faint glimmer of its existence from the previous-generation 1 TeV Fermilab accelerator.   They had a pretty firm idea that they'd find the Higgs with the LHC, and there was some hope they'd see something new and interesting out at 14 TeV.  That last part didn't work out however, and there are currently no solid predictions as to what will show up in this next energy regime.

Building this proposed collider is therefore a largely speculative step.  In the worst case, it could certainly rule out a number of theories, or at least bound them in some way that they seem less reasonable.  And of course in the best case something completely new and unknown might show up.

It's a lot of money for a slim chance at a real payoff.  Without some solid theoretical predictions that something interesting will be found, funding currently seems unlikely.  Time will tell.