On the rural side...
Sudbury - Most trains are planned to operate through to Colchester Town, hopefully given the new units are bi-mode the services will be combined with the existing Colchester -Walton-on-the-Naze local service...
I hope Greater Anglia use the bi-modes to improve off wire services and through links to London rather than being used under the wires all the time.
Felixstowe - I would suggest that the branch is largely given over to freight off peak and busstituted to save a lot of money providing new infrastructure for the growing container traffic...
Whilst I can see the argument for this. I disagree. Hutchinson Ports have not yet carried out their Section 106 obligations (lawyers or otherwise) so I would not be willing to give off peak capacity to Containers and cancel the passenger train without Hutchinson Ports spending the money on the Section 106 agreements first.
East Suffolk Line - Whilst there's an extra morning Ipswich-Lowestoft service planned, with a bit of timetable tweaking an extra PM peak hour Ipswich-Saxmundham service could operate... There are already 0744, 0809 & 0857 Ipswich arrivals yet only 1554, 1717 and 1817 departures... It's about 20 minutes from Woodbridge to Saxmundham so with a bit of tweaking 3 trains in total in the Peak hour could be squeezed in like they do in the morning.. It may mean stabling the unit on the Leiston branch for a while until you can get it back to Ipswich... I don't think the freight operates to Leiston any more...
The gap betwen 15:54 and 17:17 reflects traffic on both the Felixstowe line and the need to provide a path from Sizewell for this traffic.
Ipswich-Cambridge - An extra peak hour arrival in to Cambridge is already proposed (one assumes 0720 Ipswich-Cambridge) but sadly nothing in the evening peak from Cambridge... Again with a bit of tweaking the existing infrastructure would allow a 1700ish Cambridge-Ipswich (passing at Dullingham) to operate... Ridership on this line has rocketed since it went hourly about a decade ago... Should new stations ever get built at Fulbourne/Cherry Hinton then an extra loop and a half hourly service will be needed... And to think that about 15 years ago there were some 3 hour gaps in the single car 153 operated service!!!
I think the extra service should be provided in the evening peak as you suggest and I couldn't see why it wouldn't be as it could lead to unbalanced workings. However I would also be using some of the bi-modes to extend a few services daily to / from London to provide direct services.
Ipswich-Peterborough - Service is proposed to go hourly and be extended to/from Colchester... Given the increasing container traffic, more cross London container services being routed this way, the lack of loops capable of holding a full length container train and the constraints of Ely North Junction which is already at nearly full capacity, the 5 miles of single track Ely to Soham, and the absolute block sections Ely to Peterborough which limit capacity, I have my doubts whether this service will be able to be pathed or operated reliably...
I think an hourly service can be provided but I do not believe it can be a standard hourly pattern with the infrastructure as it stands today. There will be some shorter an longer gaps such as to provide paths for freight, particularly Class 6 Freight.
Cambridge-Norwich - Service proposed to be extended through to Stansted airport but again no extra peak hour services into and out of Cambridge... Again with the propsed Stansted-Stratford service meaning 14 trains each hour through the single track tunnel at Stansted I expect reliability will not be as good as the existing Cambridge-Norwich service...
The only way that has any hope of succeeding would be 2 trains out and then 2 in, in succession and then repeat the pattern. A maximum of 16 paths an hour. I agree it's not reliable but it is likely to fix the timetable on too many points with Stansted Airport tunnel, Stansted North curve, Ely North Jn, Trowse Swing Bridge and the single lead onto the Cambridge line at Trowse Jn plus the single line sections to Kings Lynn. As with the Ipswich to Cambridge service I would be surprised if an additional peak service wasn't provided from Norwich to Cambridge in the morning and return in the evening. I hope it goes to / from London too.
Lowestoft/Gt Yarmouth-Norwich - I would like to see both routes have a half hourly peak hour service and half hourly summer service on the Gt Yarmouth route...
Sheringham Line - Would like to see at least an extra peak hour service, which can be done with the existing infrastructure... Or ideally half hourly all day as far as North Walsham... Extra summer services are already needed on the route... Wasn't a new town (garden city type thing) proposed near this route a good few years ago???
All local trains will be either 3 or 4 car units offering a big jump in capacity... Though if the Anglia economy, and Cambridge City economy in particular, continues to perform well the extra capacity will soon be inadequate...
The route to Great Yarmouth already has a half hourly service in high summer, however quite frankly it doesn't warrant it the rest of the year save for perhaps an extra working during the morning and evening peaks grankly the load isn't there as the bus viewed as a better mode of transport with a similar journey time into the heart of Norwich. Similar for Lowestoft and Sheringham. If the capacity is needed the new trains should cover this as you note above.
The new station proposed on the Sheringham line I believe is proposed at Rackheath but realistically I do not think it will generate much train demand as its too close to Norwich. The bus is likely to be busier than the train.