Knowledge Workers
It's important to remember that during Marx's time and the beginnings of socialism/communism, the proletariat, or the industrial working class, was thought to be the historical actor. These were not poor or unemployed people, but fairly stable and privileged working people, relative to the time. At this point in history, the industrial working class no longer holds the position of historical actor, or maybe better put, is part of a larger working class that is the historical actor, but in a different way than before. The fraction of the working class that most resembles the industrial working class of years gone by are people, most with college education, working in knowledge production industries.

The industrial working class was thought to be indispensable to the functioning of the capitalist economy and thus held a great deal of leverage over the ownership class. But, after over a century of deskilling and automation, the fraction of the working class that holds the most leverage is knowledge workers since the knowledge they produce both control the automation and create the subjectivities or modes of life necessary to create the demand for goods and services.

The dominant "commodity" (and I put commodity in quotes because this commodity is profoundly different from what we think commodity should mean) in capitalist production is thus knowledge. The genetic code of a seed is now more valuable than the plant the seed produces because the genetic code controls production of all plants of that species. The seed is planted and grown in an almost fully automated way.