The 331s are coming regardless. As the 319s and 323s are both Porterbrook owned if their claim about a risk of their being more demand for 769s than they can fulfill is true, maybe they'll let Northern swap electric only 319s for 323s?
I would agree, but....
a) haven't 323s got a lower capacity being 3 car not 4 car?
b) if so, would Northern need more units to allow doubling up, particularly in the peaks
c) would that mean more platform lengthening required.
d) who would cover the cost paying for refurbishment / redecorating costs on a 2nd electric fleet.
e) would Porterbrook reduce their leasing costs on the 323s and the 769 flexes northern will have, to make it worthwhile? Maybe then Northern could retain more of the flexes for use in place of other sprinter classes where there is some under the wire running.
Its a lot of questions, particularly the last one, because unless it is going to significantly reduce Northern's operating costs, or reduce the refurbishment costs, I am not sure why they would get involved with the hassle.
Porterbrook have put their foot in it a bit by failing to read the market in new EMU rolling stock orders, and at the same time presumably not dropped their leasing costs to stay competitive. There is no doubt that the Flex unit is them trying to tap into a new and potentially very good market, and they have said that this concept may be possible on other rolling stock, whether that applies to the 323s I don't know.
However the biggest headache must surely be for the DfT, NR and Transport Secretaries both current and future. If newspapers start latching on to rolling stock built in the 1990s EMUs sitting around doing nothing or even getting scrapped, whilst commuters are sat on 1980s DMUs, the transport secretary will surely come under a serious amount of political pressure given the decisions to pause - suspend - scrap electrification schemes.