There is a lot of improvement they could do to cover more of the West Mids with the existing rail network. Just one example... The Walsall -> New Street line that goes through Witton
No station between Tame Bridge Parkway and Hamstead? WHy, its madness, there has been a need for a station on the Newton ROad since I was a small kid, there used to be one but they closed it at the end of WW2 (and less than a decade later they were building massive estates right by it)
On the same line, there's a section called the Soho Loop as an alternative to the usual route into New ST, it used to have stations for Handsworth Wood and Soho Road