What will nationalisation mean to the average fare-paying passenger?
Very little, if anything in the short term , is my best guess. Lets forget this on-line focus on 'branding', in as a new sticker on the side of one unit, or however many units going forwards. It's just part of the political spin process, end of. There are noticeably a small number of contributors to this forum who are either still in (or ex) the industry or who understand the reality of things going forward (no names, no pack drill). The reality is that the industry needs to get back to basics - running trains on time (ie: as advertised to the fare paying public), and doing so with the booked formations (or number of cars).
In relation to the latter point, the 701 roll out, formations on the suburban side in general will be fluid for as long as that process takes, so there will likely be occasions of short forms, and (regrettably) some cancellations. I would estimate that one new 10 car 701 diagram would be planned to enter service every fortnight going forward.
Going OT to a degree, but with the best of intensions to explain what I mean;
It has to be remembered that technical problems with the units aside (preventing entry to service), the planners, having already planned their various (dates) of engineering works and other alterations (mid week and weekends) well in advance of date of operation, and having moved on to their next allotted workstream(s), will have to return to previously completed workstreams and make numerous alterations there to, in (initially) stock diagram, but also associated crew diagram and timings aspects, with every new single 10 car 701 introduction (this includes diagrams changes - stock and crew in order that all stock types are 'balanced' at each location with every increase in 701 diagrams - it is rarely a simple one for one process), as the go ahead for the latest 10 car 701 to enter service will at best be perhaps two weeks notice. Any such late changes out of the norm (on a regular basis) will also involve the good will of the train crew side on the ground.
That sort of (additional) work overlapping of previously completed workstreams, is a hard bullet to swallow for all, planners, train crew, controllers etc., and can only be kept in check for so long, there is only so much overtime 'one' can work, before people doing those jobs start to lose the plot, without having additional (personnel) resources to assist.