Then again, we'd have so many more AC EMUs spair had the perfectly fine 312s not been withdrawn so early. All they needed was Central Locking, and they were as good as any unit of the sort of age in service (especially when you consider how much older stuff is still in use). AFAIK they could even have run OPO, and I'm sure they were autherised to work OPO as a single unit anyway, even without CDL, although I don't know if it was ever done. Since the ex FGE units had had a number of doors per coach sealed up anyway, CDL fitting would have been less expensive, and they had been refurbished since privatisation. Of cource, the SRA in their infinite wisdom put pressure for their withdrawal, and wouldn't allow FGE to fit door locking to them. One sensible option that is available, at least for now, is the use of hauled stock. Since the loco an DVT wouldn't have to be fully on the platform, I can't see any reason why full length electric hauled trains couldn't run on any number of routes, freeing up 2 EMUs each. As long as it's not too much of a start-stop run, full length electric hauled sets can maintain EMU timings. The only issue would be clearance for Mk3s and DVTs. The ECML is an ovious choice, since they will be fine there. Sadly Thameslink is out of the question, since they wouldn't be able to run to Moorgate, but St Pancras to Bedford is cleared for 86s, 87s, 90s to run under power, and the whole line at least as far as Wigston is cleared for Mk3s and DVTs (at at least 2 times in the past their have been sunday diversions from Liverpool to St Pancras via Nuneaton and Wigston, with the electric locos powering south of Bedford).
Whatever is done, the situation is even more important since on the GN side, 317s are already being refurbished, and their is talk that 365s will also soon start being refurbished.
Of cource, this does bring back that rumor I heard some time ago that DMUs could be used on certain Great Northern services. What with the DMU cascade from Trans Pennine in the near future, as well as when FGE get rid of the 180s, it does seem feasable. I don't see it as such a good idea as electric loco haulage though, since their are issues with length and capacity, as well as many if not more clearance issues compared to locos, and also performance issues (other than 180s, none of the available DMUs comes close to EMU performance, but 180s are unlikely to be used since a 5 car wouldn't provide the capacity and a 10 car would be too long).
We shall see. I'd put money on the fact that whatever happens, it won't be the most sensible idea.