One common complaint of the comic strip industry is that it is cluttered with "zombie strips" as well as strips that have grown stale. Examples of zombie strips would be B.C., Prince Valiant, and Sally Forth. Those strips have since passed beyond the ken of their creators and have been continued by a series of artists.
Those strips are also poor examples of strips that have grown stale. Johnny Hart's daughter and two of his grandsons now draw B.C. and their perspective has made it a strip worth reading after decades of stale writing.
The larger point is that the limited real estate of the weekly newspaper makes it terribly hard for new comic strip artists to break into the business. An example of a strip that is just dying to make the jump and most assuredly never will is XKCD by Randal Munroe. The humor is quirky. More importantly, it makes you think and takes you places you might not go on your own.
This strip from last week is a classic. I was only barely able to contain myself from whipping out a calculator to check each and every approximation. You never know when you might need a good approximation! Not only was a laughing at myself for being so obsessed, I was simultaneously awed by Randall's genius and amused at the utter waste of brilliance and effort required for him to create this strip.
As an added bonus, place your pointer over the image to read the alt text. The many layers of humor that Randall routinely rolls into his work is nothing short of brilliant.