The expected discoveries (resonances) in the energy range up to $100~$TeV depends on the theory that you decide to believe in.
None of the theories beyond the Standard Model has been experimentally validated yet. If you only believe in the Standard Model, then there are no new resonances expected as the theory was completed with the discovery of the Higgs boson.
Still the Standard Model is not totally satisfying as it leaves many open questions (matter antimatter asymmetry, candidates for dark matter, fine tunings of some of its internal parameters, ...) so we expect to have something more.
Within the framework of the Standard Model, a lepton collider at a centre of mass energy up to $\sim350~$GeV offers a number of very precise tests which would eventually allow to discover unexpected deviation or inconsistencies. According to M. Mangano a proton collider at $100~$TeV would open additional channels such as:
- Direct access to $ttH$ and $HHH$ couplings
- High-statistics and sensitivity for very rare decays like $H\rightarrow μ^+μ^–$ and $H\rightarrow Zγ$
In general compared to the high luminosity upgrade of the LHC, a $100~$TeV machine would come with a much higher statistics, which in turn gives access to different kinematical regions, with better control of backgrounds and experimental/theoretical systematics.
I would suggest to have a look at the European studies for Future Circular Colliders (FCC) which are the competitors of the Chinese designs. As starting point here is a link for a series of academic lectures that have been given at CERN in Feb 2016: https://indico.cern.ch/event/472105/. They cover theoretical physics, detectors and accelerators designs. Note that the recordings of the lectures have been uploaded as well!