Although Turbine could probably knock out a DDO implementation of it in pretty short order. It is not so different to 3rd edition from a programming perspective. Different combat script, the really tricky would be creating the enhancement table to give one the 60 or so ranks, Not sure is the audience would be there for that though.
You can't simply change the complete core mechanics of a already established game. The playerbase would rebel and DDO would be dead instantly.
And for a new game you would need a new graphics engine etc. as the DDO one doesn't cut it any more for a new release. Also, marketing would have started by now as no company can afford to get only PnP players as customers so that they could rely on the DDN release as only source of promotion. They would have to run a separate campaign which targets MMO gamers.