Seems like this the mangaka tried to express the delusion of getting axed in this last chapter a pity because it was a original story, I've seen similar plots but not like this.
There is a manga that is a mirror image of what the 3 artists were talking about in the picnic, Shomin Sample, a pretty popular manga with many chapters and a loyal fanbase, got axed without much notice from the editor because the magazine wanted to make the readers focus on Masamune revenge, a typical cliche story with a guy falling for a bitchy tsundere, I don't know what happened to the magazine after but Masamune only continued for some chapters and then ended, Shomin was axed for nothing.
At least this author didn't rage like Cleaning Gyaru and made a semi rape chapter.