A measurement of the trilinear Higgs self-coupling with a significance of at least 5$\sigma$ can only be done at the HE-LHC (33~TeV), CLIC (3~TeV) or the VHE-LHC (100~TeV), with projected precisions in the Standard Model of 15\%, 10 to 16\%, and 5\%, respectively. It would take a factor three more luminosity for the ILC to reach a precision similar to CLIC. Such an ambitious luminosity upgrade, which includes both a longer running~\cite{Snowmass} and a vigorous accelerator upgrade programme~\cite{1308.3726}, has recently been brought forward. This option had not been included in the ILC TDR, allowing for a significant cost reduction. As this upgrade could happen only after a first run at $\sqrt{s} = 1$~TeV with baseline luminosity, it is unlikely to occur before the VHE-LHC could become available. Furthermore, since deviations in the HHH coupling arising from new physics effects are expected to be smaller than $\pm 20\%$ with respect to the Standard Model prediction~\cite{cite:1305.6397}, such new physics effects could only be probed at the VHE-LHC. The VHE-LHC is also the only machine that could have a say on the quartic self-coupling~\cite{QuarticHiggs}, needed to fully understand Electroweak Symmetry Breaking.

It is worth mentioning that the ILC luminosity upgrade, for which a cost estimate is not available, includes several years of running at $\sqrt{s}=$ 500 GeV and several years of running at $\sqrt{s}=$ 250 GeV with luminosities two and four times larger than the baseline programme~\cite{1308.3726}. After the full 20- to 30-years programme of this upgraded ILC, the precision on the Higgs boson couplings to light fermions and to gauge bosons would still be a factor two worse~\cite{Snowmass} than the precision expected with only 10 years at TLEP with $\sqrt{s} =$ 240 and 350~GeV.