But reality is, without incentives, Bitcoiner's can't be expected to take/accept the opportunity cost to lock their capital, Bitcoins, in Lightning channels.
there is an incentive. It's more long-term, but the reward is bigger.
The people that provide liquidity to those who need it most will be rewarded. Those who do not will need to hope they get lucky, and that a dissimilarly self-less person provides to them some incoming liquidity.