As the Higgs fills in the last missing particle for the Standard Model, creating such a new accelerator seems very speculative. Maybe there is nothing else to find at higher energies, there is no hint of them at the LHC and the Standard model does not predict anything. I understand professionals always want more experimental power, but given the $10billion+ cost, it seems hard to justify.
Let's finish getting all the useful benefits from knowledge gathered about the Higgs boson.