Nor are all alternatives to capitalism socialism. Socialism is also known to have very severe problems in application, particularly how to incentivize socialist managers to behave like capitalist ones in most circumstances, driving innovation and maximizing productivity. Socialist managers have somewhat different contstraints on them from capitalist managers, and nominally different long-term goals, but they are more similar than you might think.
The thing is: we know how to make capitalism work in a range of varieties, from the Scandanavian social democracies to the mess that's Texas. We have never seen a successful system of public ownership of the means of production (which is what socialism is, and nothing else). It has been tried in a variety of places and times, and it has always run up against fundamental problems of managerial incentives and political corruption at levels that make most capitalist political economies look pretty good (which is saying something!)
So looking for non-socialist means of distributing wealth in a society that is unequally post-scarce is a good idea. Today wealth is distributed almost exclusively through paid work, but that is a relatively recent invention. I'm not suggesting a return to feudalism or anything like it, but think we should be willing to consider variations in social order that are at least that large-scale, because the difference between what is coming and industrial capitalism is going to be at least as big as the difference between industrial capitalism and the semi-feudal societies that preceded it in many places.