It's possible that the Northern Line could be split in two and a new name needed.
This is an old story from
The Londonist from May 2016.
The idea of splitting up the Northern line isn't crazy. It originally was two separate lines — the City and South London Railway (running from Morden via Bank to Camden Town) and the Charing Cross, Euston and Hampstead Railway (running from Kennington to Edgware via Charing Cross, with a spur to Archway from Camden Town).
The name "Northern line" came into existence in 1937, bolting together all the various bits that confuse tourists, and Londoners who aren't paying attention, to this day. Wouldn't it be easier to untangle it and have simpler routes?
That's something Transport for London have been wanting to do for a while — and a document from July 2015 (PDF) proposes the Northern line will be split by April 2023. By getting rid of the bottleneck at Camden, where lines cross over, TfL» thinks it can run 33 to 36 trains per hour. At the moment, only the middle sections approach that kind of frequency.