In a rare break from apathy , I actually submitted a comment to one of the consultations, suggesting a link from Curzon Street onto the Duddeston Line as a relatively cheap way of allowing trains to continue to Wolverhampton and other destinations, especially if it were included from the outset and not necessarily connected to all platforms. It would mean a reversal but the two lines cross anyway and it is in an area where speeds are low. Given its simplicity , I would have thought it could work commercially and provide an emergency exit to Curzon Street
I received a very general reply which didn't answer the point.
I guess the teams are now looking for ideas to remove cost rather than even modest increases, although there was a recent change to include passive provision for an additional link to Liverpool.
The original concept also envisaged a link, presumably going in the other direction to allow trains to continue to Bristol, but this didn't seem to make it to the consultation.