Longread which gives I nice overview: https://github.com/dotnet/corefx/issues/1039
DbProviderFactory: https://github.com/dotnet/corefx/issues/4571
Schema stuff: https://github.com/dotnet/corefx/issues/3423 https://github.com/dotnet/corefx/issues/5024
I don't care that much for schema as I'm not an ORM writer, but I do have used Datables a lot as a convenient data-mangler type for importing legacy data, converting data etc. They may be "dirty", obsolete or whatever but they get the job done.
But I don't get the big problem here. If someone _needs_ DataSet/Table, why don't they just pull in the reference source or Mono? That beats bringing that into the new Core API and avoids bloat. If it turns out it's too critical, put it in 1.1 or something.