I think everyone is familiar with the chronic decay going on within Nickelodeon at the moment as it continues to survive on shows that have flogged too many dead horses, along with new content that survives on toilet humor alone and yet another Hannah Montana clone that so doesn't rip off Disney Channel; but when did this all go wrong? When did Nickelodeon pull their greatest faux pas?
Well it's because of this show.

Chose that one because that's what Nickelodeon seriously needs to ask themselves right now

Yep Nickelodeon are doing crap because of Adventure Time, but why Adventure Time? Well lets go back to late 2008, early 2009 to find out.
Cartoons were going through a rough patch as they were losing popularity faster than a celebrity trolling on Twitter, so Frederator Studios, fresh from counting their money from the successful Fairly Odd Parents franchise set another series of shorts to look for new talent called Random Cartoons which consisted of a number of works from various creators mostly from the Nicktoons stable but had a few from Cartoon Network and surprisingly Doug TenNapel of Earthworm Jim fame. One of the big successes from the show was Pendleton Ward, fresh from his work on Flapjack over on Cartoon Network with another creator named J.G.Quintel, who came up with Adventure Time and another show named Bravest Warriors; the Studio needed two TV shows and a Web Show. Pendleton Ward's two shows both got picked for TV and web respectively while the third show picked was Fanboy & Chum Chum by some nobody.
Afterwards Nicktoons were keen to make Fanboy & Chum Chum but weren't so keen on Adventure Time until Cartoon Network bought it off them and premiered it a year later and the rest is history, Adventure Time along with Regular Show saved the Cartoon Industry and Nickelodeon was left licking it's wounds which keeps getting more painful everyday especially when Fanboy & Chum Chum continually get voted worst cartoon ever by pretty much every wannabe commentator on Youtube.
To sum up, Nickelodeon chose Fanboy & Chum Chum over Adventure Time and ended up giving what is currently the World's Most Successful cartoon today to their biggest corporate rivals.
I'm not even going to dignify that with a facepalm, it was such an idiotic decision that I'm kind of glad they're getting punished with crap shows. This isn't the first time Nickelodeon turned down a quality show that went to Cartoon Network, they did the same with Ed, Edd & Eddy because they wanted creative rights over it which the creator rightly refused and that became not only Cartoon Network's longest running show but one of the longest running Canadian shows.
But what about the future? Adventure Time can't be on forever and Pendleton Ward has already stepped down from the show. Well Steven Universe is a hit and Uncle Grandpa despite it's short comings is surprisingly good, heck even the new Teen Titans Go series is fun in places. As for Nickelodeon, they have more toilet humor, which is their plan for the next few years and to be honest Spongebob & Fairly Odd Parents have decayed so much in quality that they probably should quit, so expect Nickelodeon to be cartoon free in a couple of years. I'll start writing Nicktoons' gravestone now.