https://www.linearcollider.org/ILC/Publications/Technical-Design-Report
It's volume two you want. This is the report that will have been submitted presumably to those people who are about to pay the bills, so it is naturally written with more than a little bias in favour of electron colliders over hadron ones, but it is also true that a lot of the advantages are real. It's also well over a hundred pages long and very quickly gets super-technical -- if you do glance over it please do ask any questions and I'll do my best to answer them.
Anyway, the search for new physics could, possibly, continue with a different type of collider; while the measurements of properties of currently-known physics could always benefit from some retuning.
For the record, I'll also quote verbatim the report's view of the situation at the LHC, and how they justify a further experiment in light of the apparent lack of results:
* * *
"The LHC has not yet provided evidence for signals of new physics beyond the Standard Model
from its early running at 7 and 8 TeV. There are two distinct attitudes to take toward the current situation. The first is that it is premature to draw any conclusions at the present time. The LHC experimental program is still in its early stages. The accelerator has not yet reached its design energy and has so far accumulated only 1% of its eventual data set. The second is that the discovery of the new scalar boson—especially if turns out to have the properties similar to the Standard Model Higgs boson—and the deep exclusions already made for supersymmetry and other new physics models have already changed our ideas about new physics at the TeV energy scale. Our information from the LHC is certainly incomplete. We look forward to new information and new discoveries in the LHC run at 14 TeV [note -- currently just 13TeV, with 14 TeV runs expected later on] that will take place in the latter years of this decade. And, yet, we must take seriously the implications of what we have already learned."
It then notes that there are three broad types of model, the first (basically Technicolour, which I think I name-dropped in the other thread) is already almost dead, although some people are still working on it anyway. The second, the LHC should be able to see itself but if it does then you'll need a new collider to run precision tests. The third, the LHC might not be able to rule out for good -- and again a new electron-positron collider could do the job instead. So I guess that means that the LHC need not mark the end of New Physics as we know it if nothing turns up. We'll see.
* * *
Incidentally, the effort that goes into designing, building and running these things also creates plenty of jobs at all levels. It's not just scientists employed at colliders. And the global collaborative effort to make these things work and get useful stuff out of them is not insignificant either. Science can be a great unifier, and is also pretty good for the economy. Perhaps depends on your perspective I suppose. At the very least, if you have money to throw away on giving physicists fancy little toys to play with then things can't be all that bad.