I'd gladly take the 323s back over the 319s in Northernland!
I don't think we know the length of the Northern leasing deals for the 319s.
They came in dribs and drabs, and now we have the 769 conversion.
Most of the fleet is seemingly going to be parked.
There is no other practical solution for the start of electric working to Blackpool and Windermere (and probably Wigan), but I imagine Northern will be watching the options for later-model EMUs with interest.
I'm not sure there are enough 323s to replace Northern 319s, but some combination of more modern EMUs may become viable as the franchise progresses.
Northern seem to be locked into the 769 bi-mode solution though.
The 323s are unique, of course, without a manufacturer to support them.
The detailed West Midlands solution is not yet clear either.