I think the real problem is the age structure of the population is increasingly skewing older and this problem becomes worse the lower the birth rate. I don't know how we're going to keep supporting more and more people getting past the retirement age and collecting benefits on a shrinking working age population being squeezed harder by taxes. Either retirement spending goes down maybe with higher retirment age or increased healthspan, or we become much more efficient at taking care of the elderly with fewer resources, or the working class gets squeezed harder & harder.

There’s also the option of raising corporate and high-net-worth-individual tax rates!