  If the recent indications of a possible state $\Phi$ with mass $\sim 750$ GeV
decaying into two photons reported by ATLAS and CMS in LHC collisions at 13 TeV
were to become confirmed, the prospects for future collider physics at the LHC
and beyond would be affected radically, as we explore in this paper. Even
minimal scenarios for the $\Phi$ resonance and its $\gamma \gamma$ decays
require additional particles with masses $\gtrsim \frac12 m_\Phi$. We consider
here two benchmark scenarios that exemplify the range of possibilities: one in
which $\Phi$ is a singlet scalar or pseudoscalar boson whose production and
$\gamma \gamma$ decays are due to loops of coloured and charged fermions, and
another benchmark scenario in which $\Phi$ is a superposition of (nearly)
degenerate CP-even and CP-odd Higgs bosons in a (possibly supersymmetric)
two-Higgs doublet model also with additional fermions to account for the
$\gamma \gamma$ decay rate. We explore the implications of these benchmark
scenarios for the production of $\Phi$ and its new partners at colliders in
future runs of the LHC and beyond, at higher-energy $pp$ colliders and at $e^+
e^-$ and $\gamma \gamma$ colliders, with emphasis on the bosonic partners
expected in the doublet scenario and the fermionic partners expected in both
scenarios.
