We will never get a reboot because for some reason Paramount hates us, well hates us slightly less than GI Joe fans. Looking at how badly GI Joe needed a reboot and couldn't get there is no way to get a reboot out of Paramount until some leadership or something changes to say hey it's okay to reboot everyone else does it. But yea the villain well is getting pretty dry. Starscream's dead, Soundwave and most of his minions are dead, they wasted Shockwave for nothing, granddaddy of the combiners is dead. Transformers wasn't exactly hitting on many lieutenants to begin with and now it's going to scrapping up the goons, thugs, and lackeys to fill the roster. Provided it's not just more nameless genericons and Galavatron. Oh and I've always hated Galavtron as a character so that is another strike right there. We are stuck with what we are stuck with and any hope of change is just a false hope that's going to break your heart. Once Paramount has killed off all the G1 Decepticons I'm guessing it will be down to killing off Engergon, Armada, and Cybertron Decepticons so Prime and the humans can get in their required kills per film.