Seems unlikely, didn’t happen when WA inners were transferred few years ago, suggested then too difficult to change diagrams as Hert East inter worked with Camb and Stratford/Stortford services.
However, might now make more sense. Hertford East, Ware, St Margaret’s and Enfield Lock all 8 car max currently. GA required under franchise agreement to extend for 10 car 720 operation by Sept 2018. No work done, and neither GA nor Network Rail have confirmed work will be done. If not only 5 car 720s to Hert East unless 317s or other units retained. Some 317s having PRM mods done but who knows if enough will be done in time. 379s to Hert East? Perhaps but not really suited long term.
4/8 car 710s might make a lot of sense if are enough to go round. They would also be better suited to STAR all of which is 8 car platforms, although l *think* 10 car 720s will fit and use SDO. Is that right re platform 11 at Stratford? STAR bit of mystery no info on timetables yet and as discussed on other thread if not inter worked with Lea Valley services will need 2 units with long layovers at Stratford . Perhaps some Hert East services could be diverted to Stratford and units inter work with STAR?