I think any new stock replacement plan has to consider wiring on TP. Personally I think it'd be best to plan for
Manchester-Bolton-Preston-Blackpool
Liverpool-Warrington-Manchester-Leeds-York
Micklefield-Hull
and Northallerton-Middlesbrough
You then would run
1tph Manchester-Glasgow/Edinburgh ICWC w/Pendolino
1tph Liverpool-Glasgow/Edinburgh ICWC w/Pendolino
As stoppers i.e. Wigan, Preston, Lancaster, Oxenholme, Penrith, Carlisle, Lockerbie, Motherwell, Glasgow / , Haymaket, Edinburgh
allowing the hourly London Service to run Warrington-Preston-Carlisle-Glasgow
I'd then add
1tph Liverpool-Newcastle (Warrington, Manchester, Huddersfield, Leeds, York, Newcastle)
1tph Liverpool-Hull (South Pway, Widnes, Warrington, Manchester, Stalybridge, Huddersfield, Leeds, Selby, Brough, Hull)
1tph Airport-Middlesbrough (Piccadilly, Huddersfield, Dewsbury, Leeds, Garforth, York, Thirsk, Northallerton, Yarm, Thornaby, Middlesbrough
1tph Airport-Newcastle (Piccadilly, Stalybridge, Huddersfield, Leeds, Garforth, York, Thirsk, Northallerton, Darlington, Durham)
1tph Picadilly-Hull (Huddersfield, Dewsbury, Leeds, Selby, Brough, Hull)
1tph Airport-Blackpool/Barrow
1tph Airport-Liverpool (Picadilly, Oxford Rd, Irlam, Birchwood, Warrington, Widnes, South Pway, Lime St)
all operated by 5-car 344s (444s with pant.)
some 185s would still run the South TP services, while others could be used on new routes, e.g.
Bradford-Halifax-Todmorden-Victoria-Newton le Willows-Liverpool LS
Scarborough-Malton-York-Garforth-Leeds-Bradford Int-Halifax-Sowerby Bridge-Burnley M Rd-Accrington-Blackburn-Preston-Poulton-Blackpool