Google didn't say that YouTube, Blogger, or Google+ have taken Orkut's place. Google said that YouTube, Blogger, and Google+ have outpaced Orkut's growth and are, largely as a result of that, more appropriate focuses of Google's resources.
> I'm thinking more that non-Google services are the real threats
This isn't about "threats", its about opportunities -- more specifically, its about where Google effort has the best returns for Google.