An interesting question is what will happen to the Stourbridge branch. I just had a ride on it this afternoon[1], and the units are looking and sounding incredibly knackered. Perhaps a good place for another 230? Even perhaps a battery powered one?
Re the 172s they are quite nice but suffering from the Bombardier (former Adtranz) build quality issues as most Turbostars do. But re-powder-coat all the panels and metal stuff and add armrests and tables, and remove the side-facing seats and respace the existing ones, and they'd be quite nice regional express units. The seats are decent enough in and of themselves.
[1] Using a LM free pass I got two of for allowing them to use a Tweet I sent about their Wifi being better than VT's on a poster, which they haven't actually done but have sent me the passes anyway. Amusingly when I scratched off 2017 underneath was printed 2014. The only guard to question it so far (it looks incredibly faked) was the one on the PPM!