The gulf between DirectX 11 and the DirectX 7 that Orbiter currently uses for stock graphics is immense, and transferring from one to the other will be no mean feat. There is however a DirectX 9 client in development which has currently achieved some good results, and there is the potential to build on that work to move through to DX 10 and eventually DX 11, perhaps, but the differences are still substantial.
You can check out the DX 9 client
here - it is currently at Release Candidate level of development.