DXO seems to be interested in doing a real plug-in for Lightroom once the SDK is released. Is the due for LR version 2?
This is encouraging for those of use that like some of the Optics Pro features; however, I seem to recall some mention that Adobe's intention (and I have no inside knowledge) was to allow 3rd parties to write full modules (ie Develop, Web etc.) not add-ins to the Adobe modules.
I don't think it would be easy to allow DXO to do noise reduction on the raw file, switch to the ACR engine for demosaicing, tone and colour, then over to DXO's lens corrections. I would love to see this kind of flexibility, but it would seem to be complex to implement. If DXO v5 really has improved demosaicing and noise control then perhaps I wouldn't mind using it in place of the Adobe Develop module, but currently I prefer the ACR engine for raw conversion.
What I would love to see is sort of analogous to VST plug-ins for an audio stream, where lots of different effects can be put in any sequence you want. With images you would effectively have a section with Bayer mosaic data, then post demosaicing, a stream with RGB data. This could end up very complex for the end user as well as the developers, though so I doubt it will happen that way.
Richard