There is theoretically scope for a small reduction in 700/0 work.
The current service calls for 25/30 379s and 8/13 387s, though in practice there’s one fewer 387 due to 387101 being long-term out of use, three extra 387s not yet transferred to Southern, and this isn't what is currently being resourced due to the 379 fleet not being at full strength yet.
Remembering that the 365s were diagrammed for 37/40 (or was it even 38/40 at one point, I can’t remember), albeit quite often with 317/321 covering, so this isn't a heavy demand on the fleet.
So 27/30 379 and 10/13 387 ought to be easily possible. That would theoretically reduce 700/0 usage by two. Where thing could get muddied is if the Peterborough peak extras need to be increased to 12 cars (currently only one is each way), in which case either extra 700/1 need to be found, or there would have to be some shuffling round to allow 387/379 to take over any 12-car workings. In theory this doesn’t preclude more 387/379 staying out between the peaks, but it makes things more awkward as there would have to be some additional 4-car working to/from Hornsey.
If we’re going to place a bet on it, I’d say the current mix will stay, perhaps in a year’s time there might be one more 387 pair out on the 2C/2L between the peaks, but probably unlikely to be more than that. What is more irritating in the current timetable is the 387 workings tend to be more bunched, so there are long periods where successive services are 700/0. I'm fortunate that my regular patterns tend, by good fortune, to lend themselves to the two 387 pairs.
To ditch all GN 700 working would require something in the region of 20 Electrostar units, so is unfortunately unlikely to happen unless something else forces a change.
