A more updated version would be that neoliberalism is the opiate of intellectuals. Much (but certainly not all) of Marxism has held up rather well in retrospect (especially teh critique of capitalism), especially in the conditions we face in 2020.
In this case, evidence that requires time to collect and events to play out are a realm of uncertainty and ambiguity are frequently played on when comparing capitalism to historic other systems we know "didn't work."
At the same time, you'll have many who understand that those levels of uncertainty and ambiguity can be gamed to their favor and will support which ever options of the uncertain benefit them the most, regardless of what they may believe to be true.
For some reason were so confident and or arrogant that we "have it right" while others have it wrong. Meanwhile, we look at macroscopic trends that are toxic and continue preaching dogma.
When we talk about the scale of economic systems and societies, there's a lot of uncertainty of how any axiomatic rules result in macroscopic/emergent behaviors that we see. It's so complex it's often incredibly difficult to look at macroscopic behaviors we dont want as a society and walk them back to first principles or lower order principles that causes the issue to fix them. For some reason though, it feels like as society we don't try to fix them or those who play on uncertainty and fear to their advantage seem to always win everyone over.
Capitalism is extremely good at a lot of optimization problems and squeezing out efficient solutions. The issue is that it has to be well constrained to optimize for what we want and not optimize for things we don't value as society. General health and well being seems to be one of those factors we're not optimizing well for.
The real opiate of the intellectuals is any system that gives you the belief that you've got things mostly figured out. Neo-liberalism definitely qualifies for some, but so does Marxism.
However, given the current state of things, there's probably more value to be had now from reading Marx than some venerable free market tract. Just don't let it go to your head.
This is a critique that left-anarchists have always had of Marxisms. However, Marxism also has a point that a complete economic overturning is impossible without force, necessitating a vanguard anyway. So, I don't think anyone can remotely say what comes after our economic system.