The discovery of the 125 GeV Higgs boson sets a new era in high-energy
physics. With the observation of this particle, the Standard Model is
a complete theory, and the Higgs sector should be studied in all its aspects.
This investigation, already on going at the Large Hadron Collider (LHC), will
continue also with the LHC upgrade luminosity programme, HL-LHC.
The main physics prospects at the HL-LHC, and at the future collider experiments
proposed by the high-energy physics community to continue these investigation
after LHC, are presented and discussed.