Where'd you hear that? It's absolutely not true. The LHC itself has been upgraded several times during its life and there are several designs for next generation colliders (such as the Future Circular Collider).
There was a major upgrade in 2013-2015 which doubled the energy (from 3.5 TeV per beam to 6.5 TeV per beam), but the luminosity was increased in 2016 and 2017 as well.
> There was a major upgrade in 2013-2015 which doubled the energy (from 3.5 TeV per beam to 6.5 TeV per beam)
Yeah, that was the splice consolidation.
> but the luminosity was increased in 2016 and 2017 as well.
From what I know, that's through conditioning, repairs and improved techniques (BCMS, ATS, anti-levelling). The increase from 2015 to 2016 was because they didn't finish the intensity ramp in 2015 as the scrubbing campaign lasted so long. 2016 had the TIDVG dump problem as well as outgassing from the injection kickers. 2017 was marred by 16L2.
