The author commits the cardinal philosophical sin of not defining his terms. What exactly is "postcapitalism?"
"Capitalism" is simply the description of who owns the means of production (regardless of the good). Namely that individuals without legal means of physical coercion control production rather than a state with the legal means for physical coercion. So anything that is post-capitalism by definition means that production isn't held by individuals - which is the opposite of what the author seems to be advocating for.
Markets exist irrespective of whatever the formal mechanism of trade is sanctioned by the state. So even in the most socialist/communist of systems, there exist markets. It just happens that in those systems the state has the plurality of pricing controls (ie. controlling supply and demand). In fact the more top-down controls there are in a market the more there are non-sanctioned, non-connected markets (black & grey markets as an example).
The author seems to be saying primarily that there is an increasing number of grey and black markets that are forming and being utilized because the official sanctioned markets are "failing." Ok, nothing new here really other than speed and scale.
This is how capitalism works. Markets will clear eventually, and it will probably be really bad for a lot of people. There isn't a "solution" to this. People will need to adapt to the demands of the people around them, as has always been the case.