https://www.brookings.edu/articles/sources-of-real-wage-stag...

There has been some increase in capital's share of income, but economic analyses show that the cause is rising rent and not any of the other usual suspects (e.g. tax cuts, IP law, technological disruption, regulatory barriers to competition, corporate consolidation, etc) (see Figure 3):

https://www.brookings.edu/wp-content/uploads/2016/07/2015a_r...

As for AI's effect on employment: it is no different at the fundamental level than any other form of automation. It will increase wages in proportion to the boost it provides to productivity.

Whatever it is that only humans can do, and is necessary in production, will always be the limiting factor in production levels. As new processes are opened up to automation, production will increase until all available human labor is occupied in its new role. And given the growing scarcity of human labor relative to the goods/services produced, wages (purchasing power, i.e. real wages) will increase.

For the typical human to be incapable of earning income, there has to be no unautomatable activity that a typical person can do that has market value. If that were to happen, we would have human-like AI, and we would have much bigger things to worry about than unemployment.

I think it's pretty unlikely that human-like AI will be developed, as I believe that both governments and companies would recognize that it would be an extremely dangerous asset for any party to attempt to own. Thus I don't see any economic incentive emerging to produce it.