Did Karl Marx's theories on centralizing credit have anything to do with our current central banking system?
Karl Marx's theories on centralizing credit did not directly influence the development of modern central banking systems, but his ideas about the role of credit in the economy have had some influence on economic thought more broadly.

Marx believed that credit was an important tool for the working class to gain control over the means of production, and he saw centralizing credit as a way to counteract the influence of the bourgeoisie. He believed that a centralized credit system controlled by the workers would allow for the financing of cooperative enterprises and the development of a socialist economy.

Today's central banking system, however, has developed largely in response to economic and financial instability, and its primary role is to manage the money supply and regulate the banking system in order to promote economic stability and growth. While central banks do play a role in managing credit, they are typically not directly controlled by the workers or any other particular class.

It's important to note that while Marx's ideas have had some influence on economic thought and policies, his views on centralizing credit and the role of the state in the economy are not universally accepted, and there are many other factors that have shaped the development of central banking systems.
What would Marx think of modern crypto systems?
Karl Marx, the philosopher and economist, died in 1883, so it's impossible to know his exact thoughts on modern crypto systems. However, based on his ideas and writings, it can be inferred that he would view crypto systems in the context of capitalism and the distribution of wealth and power.
Marx believed that capitalism was an exploitative system that benefits a small group of owners at the expense of the working class. He would likely see crypto systems, with their decentralized and largely unregulated nature, as a means for the wealthy to evade government control and accumulate even more wealth and power.
On the other hand, Marx might also see the potential for crypto systems to disrupt the traditional financial system and redistribute power and wealth. For example, crypto systems like Bitcoin offer the possibility of creating a decentralized and democratized financial system that operates outside of traditional banks and financial institutions.
Marx's thoughts on crypto systems would likely depend on his view of their potential to challenge or reinforce the existing distribution of wealth and power within society.
It is worth acknowledging that Marx's economic theories are primarily rooted in philosophy and academia, and have been largely discredited over time. Despite Marx not explicitly endorsing the repression, poverty, and violence observed in numerous communist regimes, it has been suggested that his theories are blind to human nature and societal motivations, ultimately leading those who follow them toward a more oppressive system than what he aimed to eradicate. It is probable that Marx's perspectives on cryptocurrency would be similarly theoretical and lacking of true insight into its real-world socioeconomic implications.