I just checked
CityPopulation.de which is the source used for city populations on this website and it looks to me like we have three new megacities!
Zhengzhou, 10,300,000
Rhine-Ruhr Area, 10,900,000
Taipei, 10,100,000
Am I wrong or did I just find new megacities?
In other news, I'm finally glad they merged the entire Rhine-Ruhr instead of having "The Ruhr" and "Dusseldorf/Cologne" as separate entities.