Looks like an article from The Inq about DirectX 10.1 was wrong, Microsoft says DirectX 10.1 will definitely work on current DX10 generation graphic cards:
Microsoft's Sam Glassenberg told Next-Gen in a phone interview, "DX10.1 fully supports DX10 hardware. No hardware support is being removed....It's strictly a superset. It's basically an update to DX10 that extends the hardware functionality slightly."
He said that the update is similar to what Microsoft did with DX9. "We did make updates to [DX9] that extended the supported feature set.
"All the hardware is still supported, all the games still run, all the features are still there, we've just simply extended the feature set and the lifetime of the API," he said.