Is there an overall plan and timetable?
What are the logical next steps after F2N?
Which other container port routes could justify electrification?
These questions don't seem to entirely follow on from the thread title.
Electrification of F2N only makes sense alongside other major works including sorting out Haughley Junction, doubling the Soham section, re-modelling Ely North, re-building the Leicester area through from Syston to Wigston and upgrading or removing dozens of level crossings. These are not yet in a single plan or timetable (or funded).
Further steps would presumably include electrification of the Peterborough-Spalding-Lincoln-Doncaster 'Joint Line' for electric intermodal services to continue north to Yorkshire terminals, etc.
A couple of kilometres of electrification into London Gateway would be very useful.
So would an electrified solution for freight between Reading and Southampton via various routes (as recently exercising another thread in the Infrastructure section).