Its accelerating the real reason for electrification to Selby in the first place - providing an electrified diversionary route from Doncaster via Hambleton Junction and Crossgates to Leeds. Its also possible that Temple Hirst Junction via Selby to Hambleton, and Hambleton via Gascoign Wood and Sherburn to Colton Junction is on the agenda to provide a diversionary route for the 2 track Selby diversion section of the ECML.
I think the Trans-Pennine electrification is being planned at York, that is everything east of Stalybridge. It cannot all be done in one go and the idea is that the electrification team, which will be new, will gain experience by starting on the 'easy' bit east of Leeds. They will really have to get moving and let some contracts soon to have any wiring in place by Dec 2014. It will give EC some flexibility for diversions and would free up a few DMUs. Northern has 24 EMUs in West Yorks and probably with some re-diagramming could cover Leeds-York and Leeds Selby locals with electric stock, perhaps through working from Bradford F.S./Skipton/Ilkley/Doncaster and terminating DMUs from the west at Leeds (just swapping around what happens at present).