The reason why both TYT and MYM were cancelled because there's no clear direction to the main storyline, and Hasbro tried to connect the timelines between G4 and G5 which became a disjointed mess. The continuity between both generations felt far too out of place, and some of the episodes felt incredibly rushed. And I seriously doubt G6 will ever mark its comeback, especially since the brony fandom as a whole has diminished considerably and many folks have since moved on.