Well, that really varies. Some novels might incorporate a dictator for plot purposes, but many don't. It all comes down to the author's imagination and the story they want to tell.
In a fictional rise of a dictator story, often there are common elements. First, there might be a period of social unrest. This unrest gives the dictator - to - be an opportunity to present himself as a savior. For example, he may promise stability and security which the people desperately crave. Second, he starts to gain a following by using powerful and persuasive speeches. He manipulates the emotions of the masses, playing on their fears and hopes. Third, he gradually undermines democratic institutions. Slowly but surely, he takes over the power of the media, the judiciary, and the legislative branch, until he has absolute control.
I don't think so. There haven't been any official announcements or indications that the HxH manga will continue. But you never know, maybe there'll be a surprise in the future.