There hasn't been any news of a successor to Simcity, the current game is Simcity (2013) and Simcity: BuildIt (2014) for mobile devices.
I blame EA on that one, because they botched Simcity (2013) with an always online mode, made city maps smaller, and technically lied about the game's features and other details I'm not going to delve into. But after the game was released, there was heavy criticism of the game that led to sales slumping. After that, Maxis studio was closed and restructured and people have been left wondering whether or not will see a new game.
But if there is a new Simcity game on the horizon, my guess it would share styling and mechanical features from Simcity (2013) with a mix of Sims 4. Specifically the characters, like the last two games if I recall.
