  A quantitative discussion on the future prospects of the 750 GeV resonance at
the LHC experiment is given using a simple effective field theory analysis. The
relative size of two effective operators relevant to diphoton decays can be
probed by ratios of diboson signals in a robust way. We obtain the future
sensitivities of $Z\gamma $, $ZZ$ and $WW$ resonance searches at the high
luminosity LHC, rescaling from the current sensitivities at $\sqrt{s}=13$ TeV.
Then, we show that a large fraction of parameter space in the effective field
theory will be covered with 300 fb$^{-1}$ and almost the whole parameter space
will be tested with 3000 fb$^{-1}$. This discussion is independent of
production processes, other decay modes and total decay width.
