Well I think in some ways the 'masters' would have been the focus of the rest of Season 4. Maybe the Pretenders are founded toward the end or middle of Season 5. Although I still think at that point, it would be time for a reboot or change or something to 'revitialize' the series, considering 5 years is still pretty long for a sci-fi cartoon. So they would probably bring back Megatron somehow and essentially it would go back to a very Season 1/2 feeling. With Autobots fighting Decepticons with some of the newer races. Possibly even introducing the Pretender shells or something toward the end of season 5. Season 6 would see them gradually downgrading their sizes, kinda being like a precursor to what would become mini cons. Then Season 7 would see the destruction of Cybertron and maybe the end of Prime and Megs/Galvy and Cybertronians would colonize a new planet. Which COULD lead into a 'Beast Wars' like series set farther into the future.