Engines will be the ones being developed for 7E7 - both GE and RR are on board for doing this. Central wing box will be made of composites instead of metal. Most accounts also have a reshaped wing. All this is being done to make a A330-200 sized plane that is competitive in the regional market.
The main debate seems to be whether the tweaks above are sufficient or if a whole new plane will be made. As Mr. Forgeard says above, that has yet to be decided, either is possible.
--ev--