Though of course if that happens what on earth are VTEC (or whoever) going to do with the thirteen 9-car and ten 5-car bi mode IEPs? I mean if you forget about portion working the 5-car units so they run around as 10-car all the time that's still eighteen trains to replace the HST fleet. And don't forget that there are thirty 9-car and twelve 5-car pure electric IEPs as well!
They kinda need to run these extra services at some point otherwise there's going to be a lot of units sat around...
I maybe didn't explain myself very well (as usual!).
I was meaning something along the lines of "if the Thameslink changes mean conflicts south of Peterborough and NR aren't providing the additional capacity required to accommodate these... and this slows down VTEC services - using
coppercapped's comment about them basing plans on getting Edinburgh services down to 4h duration ... then this could easily cost an extra unit or two ... given that VTEC may be running six trains through Peterborough some hours ... it only takes a few minutes extra until you need to throw an extra diagram into the PVR to maintain timetables ... but VTEC's supply of IETs is fixed ... so that may mean having to trim something from the extremes of the network to cope with the additional time required to do Peterborough - Kings Cross - Peterborough ... "
Or, to look at it another way, due to Thameslink changes, EMT need extra trains just to maintain existing frequencies/ destinations - the HSTs arriving from GC aren't going to be used for anything interesting like extend services to Leeds - they are just there to allow them to meet existing commitments (as services are slowed down at the southern end of the MML...
...due to Thameslink changes (and lack of corresponding infrastructure improvements), VTEC may need extra trains just to maintain existing frequencies/ destinations - the IET order was based on planned increases in destinations happening - so, unless there are more IET being ordered that could mean an extra train or two thrown into diagrams just to provide the planned frequency through Peterborough ... and if supply of trains is finite then something's got to give ... and that may mean shaving off some of the planned return trips from Leeds to Huddersfield/ Bradford/ Harrogate and back - or from York to Middlesbrough.
I hope it's not the case - but it wouldn't take much additional time south of Peterborough to require an additional train to be thrown into the mix to maintain six services per hour on that stretch - and if there aren't any additional trains then you have to look at "where could we remove a train from services further north to find resources at the London end of the route".
Phew!