Just to echo the MU comments, some Civity family units would be nice please.. 195/196/197/331/397 the DMU variants all have similar chassis and identical bogies (?) and the EMUs do too, I know the 196s are slightly shorter but the 195 and 197 beyond the cab ends are very similar.
Probably not as difficult to produce either, especially compared to the FLIRTs with all their bendy bits.
I think priced right, these would nicely compliment other models in the pipeline.. especially as they are (hopefully!) going to be around for at least another 30 years, plenty of time to recoup tooling costs..!