That's not a bad point with regards to the stopping patterns: the stretch between Newcastle and Edinburgh seems to be one of the final frontiers of non-clockface inter-city timetabling. I know Morpeth is cited as one of the calling points on the new TPE services, however I do wonder how the locals would react to losing services from the XC and East Coast franchises in favour of a more standardised timetable all round and gaining a better service but only on 'local' services. The rail user group at Morpeth reacted rather angrily to losing an attractive train from London in the evening (or something similar) when Eureka! was implemented, and it ended up getting changed, so I can't imagine on that basis they'll take any loses towards London or Birmingham nicely.
Never thought about that, and of course you are correct that frequent CrossCountry services via Berwick are a relatively new creation. I suppose that does make sense and as you say would allow for more doubled up services through the network core closer to the Midlands, subject to having the correct staff numbers available etc, with say the final few trains at night and the first few in the morning coming to an from Edinburgh, which also then of course keeps the need for some staff to be based there and doesn't leave them trying to find a home for several dozen Drivers and Guards.
In Theory, you could have the Aberdeen and Dundee trains still run as per normal.
Example:
Southbound in the mornings from Newcastle in order
1V83 0625 NCL - RDG
1V48 0645 NCL - PLY
1O84 0725 NCL - SOU
1V50 0606 EDB - PLY (HST)
1V85 0625 EDB - RDG
1V52 0601 GLC - PLY
1O86 0935 NCL - SOU
1V54 0632 DEE - PLY (HST)
1V87 1035 NCL - RDG
1V56 1042 NCL - PLY
1O88 1135 NCL - SOU
1V58 1144 NCL - PZN
1V89 1235 NCL - RDG
1V60 0820 ABD - PZN (9 car set from NCL to PLY)
1O40 1335 NCL - GLD
1V62 1343 NCL - PZN
1V91 1435 NCL - RDG
1V64 1442 NCL - PLY
1V96 1535 NCL - RDG
1V66 1541 NCL - PLY
1V93 1635 NCL - RDG
1V68 1641 NCL - PLY
1O94 1735 NCL - SOU
1V70 1741 NCL - BRI
1M72 1835 NCL- BHM
1V71 1843 NCL - BRI
1M76 1935 NCL - BHM
1M00 1942 NCL - BHM
Northbound arriving at Newcastle
1E34 Ex Derby arr 0838 forms 1O86
1S31 Ex BHM arr 0927 forms 1V87
1E38 Ex BHM arr 0947 forms 1V56
1S33 Ex BHM arr 1030 forms 1O88
1E42 Ex BHM arr 1045 forms 1V58
1S35 Ex BTH arr 1129 forms 1V89
1E79 Ex GLD arr 1145 combines with 1V60 to form a double set as far as PLY
1S37 Ex PLY arr 1229 forms 1O40
1E82 Ex RDG arr 1245 forms 1V62
1S39 Ex PLY arr 1329 forms 1V91
1E86 Ex WIN arr 1345 forms 1V64
1S41 Ex PLY arr 1429 forms 1V96
1E32 Ex RDG arr 1445 forms 1V66
1S43 Ex PZN arr 1529 forms 1V93
1E36 Ex SOU arr 1545 forms 1V68
1S45 Ex PLY arr 1625 splits, with front portion departing for ABD at 1637, rear portion forms 1V96
1E40 Ex RDG arr 1645 forms 1V70
1S47 Ex PZN arr 1725 forms 1M72
1E44 Ex SOU arr 1745 forms 1V71
1S49 Ex PLY arr 1833 splits. Front portion to DEE dep 1840, rear portion forms 1M76
1E48 Ex RDG arr 1845 forms 1M00
1S51 Ex PLY arr 1932 dep 1935 to GLC (HST)
1S52 Ex SOU arr 2001 (Terminates)
1S53 Ex PLY arr 2032 dep 2035 to EDB (HST)
1E56 Ex RDG arr 2042 (Terminates)
1S55 Ex PLY arr 2128 dep 2135 to EDB
1E60 Ex SOU arr 2144 (Terminates)
1E64 Ex RDG (Terminates)
That should work, leaving enough spare sets to double sets up through the core, while the off peak daytime traffic North of Newcastle is handled by VTEC and TPX. HST diagrams unaffected. Aberdeen and Dundee runs plus one Glasgow run per day each way also unaffected
Codes:
NCL = Newcastle Central
EDB = Edinburgh
RDG = Reading
PLY = Plymouth
SOU = Southampton
GLC = Glasgow Central
DEE = Dundee
PZN = Penzance
ABD = Aberdeen
BRI = Bristol Temple Meads
BHM = Birmingham New Street
BTH = Bath Spa
WIN = Winchester
GLD - Guildford