Existing Uckfield line, or existing Brighton Main Line? If the latter - that was covered in the announcement that they're planning to take forward the upgrades to the Uckfield line (ie, the BML is pretty much done in terms of being able to increase capacity).
If the only thing that comes out of this is restoring the existing Uckfield line to dual track and electrifying, I'll be happy. With the amount of housing development taking place around Uckfield the diesel single track won't be enough within the next 5 to 10 years.