TfL have confirmed that they have begun consultation with the City of London on proposed retunnelling works at Bank station.
Although full details are not yet available, it appears that the intention is to carry out retunnelling work on the Northern Line in order to increase capacity on the platforms and provide additional entry and exit routes. This would include a number of high-capacity lifts down to platform level (handily providing step-free access as well).
The plans apparently include the opening of a new entrance to the station on King William Street in addition to that currently being developed onto Walbrook for the Waterloo and City.
Obviously the plans are in a very early stage – no Transport & Works Order has been sought yet and no work is anticipated before 2015 – but its potentially welcome news nonetheless. Bank has seen a massive increase in interchange traffic since 2003 (up over 43%) and is thus increasingly prone to congestion closure.