WW Norton & Company, Inc. is the publisher of The History of the ___ World series.
While there are general plans for future volumes to complete the series, you may be able to prod the publisher to commission the rest of the series. Contact WW Norton directly to ask when they plan to publish the next volume of HOTW. Customer interest influences publishing decisions.
WW Norton has made the existing audiobooks available on Audible, and at least one of them on Apple Books and Google Play.
We'll update this FAQ when we have further information.