In message , Paul Terry
writes
Almost certainly, as the proposed terminus of the extension at
Battersea is only two-track, which would not be sufficient for turning
back the full peak-time service of the CX branch. I don't think any
service pattern has yet been proposed, but I guess that it might well
involve alternates trains turning at Kennington and Battersea.

The four proposed routes (of which number 2 is the preferred option)
can be seen in:

http://northernlineextension.com/med...ons_lr_pages.p
d
f
Sorry but this link just gives me a 404.
--
Clive