I don't think anarchism is realistic in any long term sense. Someone will always come around and consolidate power by forming(and forcing people into) a government.
Zapatistas have around 30 years and they seem to be very close to Anarchism, Rojava has 10 years of democratic confederalism which is Libertarian socialism and let's say fairly close to Anarchism.
Gotta start somewhere, capitalism in it's current form has only been around for a few hundred years at best. Too many people have bought into Fukuyama's The End of History imo.
Anarchism as a thought has only existed for about 150 years, capitalism for maybe 500 years and still took a couple hundred to get going, so I don’t know what your standard is except to doubt that anything can come after it
