if you use non-custodial solutions. To make a lighting channel you would need to make a onchain tx. Theres 8 billon people in the world even if a 1/2 of them want to be using lighting it wiuls take 4B txs. At 7 tps (so 100% of the blockchain blocks being used for the newcomers) it would take about 20 years. Once that 20 year period is up, half the people in the world, only have 1 Channel open, which is probably going to be a speicfic entity that is routing to a lot of other people (centralized).