The capitalist system will collapse under the weight of its internal contradictions, and soon, because of its accelerating rate of development
Capitalism has gone from crisis to crisis and from strength to strength
A leadership of the proletariat would arise in the most advanced capitalist country in the world (Germany at the time) and start a Communist revolution
The revolution in Germany brought the Nazis to power and the proletarian revolution started in Russia, the most backward capitalist country in the world
That revolution would sweep the world
The "Communist' revolution was held to one country for 30 years until Russia gained control of several other countries as the spoils of war, after which it exported revolutionary expertise to some other mostly backward countries, and observed the independent rise of a similar, but later antagonistic, proletarian revolution in China, another backward capitalist country
It would end the exploitation of any class by any other class
The proletarian state in all cases has shown up a loophole in Marx's definition of class, so that the class which nominally "owned" the means of production could still be exploited by the class which objectively controlled those means through a coercive and repressive state apparatus
As a result it would lead to a life of maximum fulfilment for all of humankind
The exploited and repressed populations fared so badly that most were led to believe (wrongly) that they would have more fulfilled lives if they returned to capitalism