Concerning the cancellation of this show...
Aside from a decrease in quality with Season 3, which contributed to a drop in this show's overall viewership, I also firmly believe that lead star Rowan Blanchard also contributed to the cancellation of "Girl Meets World" as well with her outspoken and often inflammatory comments toward some fans and Disney Channel executives. I'm sure that most of her rhetoric had Disney on their toes at times knowing that her online behavior might hurt their image. On that note, I can honestly see her as one of the reasons why this show was cancelled...although it remains a mystery if she was a part of it or not. That reason lies with Disney...of which we'll probably never know.
Moreover, I've always heard that speaking out on political issues could be harmful toward a person's career, especially when you're a celebrity. When Rowan first started speaking out, the media immediately praised her by calling her "cute" and "wise beyond her years." It rather seems to me that she's just a confused and arrogant person that's looking to shove her opinion down everybody's throats.
With that being said, I can only imagine that the media will keep up their praise of Rowan until she turns 16 or 18 years old, when everything stops being "cute." By then, if she doesn't blacklist herself from any major roles (if she hasn't already) then she'll likely fade out of the limelight like so many other child actors have done.
In summary, aside from Rowan's beliefs being different from mine, this wasn't a bad show and I did watch every episode, but I would've been happier to see it move to Freeform for a Season 4, as Disney was truly bringing the quality of this show down.