A plan doesn't have to be complicated.
"Capitalism" is the wrong target. It's an emergent phenomenon of unfettered growth and the competitive moral turpitude of bullies who start with an advantage of some kind.
The target should be the growth and the consumptionism. If humans worked collectively to support and improve the world (Think "terraforming" on Mars, but we're already here.), then it wouldn't matter how many people, or which ones had the money because everyone would be working to improve the lot of the resources under their feet and the people closest to those resources.
UBI based on sales tax: because UBI without sales tax only feeds the growth of speculators and inflationists, and sales tax without UBI is regressive.