His belief was that on one hand capitalism was/is absolutely necessary to create sufficient wealth to make redistribution viable (he made the point in The German Ideology that a redistribution before that point would do what we saw e.g. in the Soviet Union: simply spread poverty around, and restart the class struggle it tried to erase as people tried to et out of poverty), on the other hand it would in its end-stages lead to "overproduction" combined with mass unemployment as it would fail to reconcile the need to try to win more of the market with the need to cut employment costs.

The ways society could prevent this happening are many, including things like basic minimum income as you suggest. But Marx argument was that societal changes of this magnitude tends to instead result in increasing tensions until revolutions erupt for the reason that ruling classes rarely see the gravity of the situation until it is too late.

There are many ways he could be wrong about this, but I find it very interesting to observe the increase in frequency with which this issue of automation and its consequencs is now coming up again.