It seems that Amazon is currently listing Uncle Scrooge Timeless Tales #4 as being out of stock, and with a scheduled release date of January 1, 2035: www.amazon.com/dp/1684051320?tag=viglink20248-20. So, why is that? Has the book been cancelled?
It was cancelled. As have any other Timeless Tales collections. That's why the third Mickey squeezed in nine issues - so it would complete the IDW run of that title. Unfortunately, it was too late for the third Donald to do the same.