Of the little that has been said officially, the DfT made it clear in the franchise winner announcement that there'd be "100 new carriages on the Cross City line". The DfT said these new units on Cross City will have "standing room for 50,000 passengers in Birmingham in metro-style carriages, similar to the ones used on the London Overground, for short cross-city journeys". If there is not to be a massive reduction in seating on the Cross City with this (DfT talk of "20,000 extra seats for rush hour passengers in Birmingham", don't admitttedly don't specify where) I think it is inevitable that almost every diagram on the Cross City will have to run as a double set.
Even now you could do with running everything departing New Street between 1600 and 1830 in either direction as a 323x2. Come 2020, with a reduced amount of seating on each new unit, the idea that you could run anything but predominantly double sets seems incomprehensible and highly unlikely to me given what the DfT have said.
There's also been speculation about where the new diesels are going. Lets not forget again that the franchise winner announcement expressed clearly that there's be "80 new carriages
for the Snow Hill line".
All this can be found here:
https://www.gov.uk/government/news/...ly-1-billion-is-invested-in-midlands-services
I still think it'll cause a stink. Though I don't imagine it'll all be transverse seating, which might appease the large number of people who travel to and from the extremities of the Cross City line, Lichfield, Redditch and eventually Bromsgrove.
