There is no DX10
The next API by MS is WGF which is finished according the last informations on it.
But this one is no DX anymore and won't be compatible to pre Win2k systems.
DX9c has enough of stuff that OpenGL has not as standard ( there are a lot of things you some of the GPU manufacturers have but lot of extension stuff is card specific ), so for the last 1-2 years enough things that OpenGL will have to take care off.
The next API by MS is WGF which is finished according the last informations on it.
But this one is no DX anymore and won't be compatible to pre Win2k systems.
DX9c has enough of stuff that OpenGL has not as standard ( there are a lot of things you some of the GPU manufacturers have but lot of extension stuff is card specific ), so for the last 1-2 years enough things that OpenGL will have to take care off.