For Mac and Linux OpenGL has a future ... for Windows, I don't think that it will survive the jump to longhorn ( it didn't even survive the jump to .NET )
You can use OpenGL in .Net - what are you talking about?
and Managed DX9 IS OO!
Yes, managed DirectX is, but that's different. Managed DirectX is a Rapid Application Development wrapper around DirectX with basic stuff like model loading. It's very rarely used in games and even the most simple game engine will replace the functionality - in an OO style, if you wish. I'm sure the Max 3D engine will be OO in design too.
As for the future of OpenGL in games, many people are predicting that the stripped-down OpenGL:ES will take over in future, especially as that will be what is used by the Nvidia chip in the Playstation 3.