This seems kind of unexpected, but I guess the sheer age of the 15X units will force their hands at some point...
Whilst the 195s were a welcome refresh, they didn't even have enough capacity for today, nevermind a 'growing' railway. 331 order seemed actually adequate, which was unexpected!
Guessing we can expect a fair few more Northern services to go electric over the next 10 years, with electrification of Manchester-Leeds and Leeds - York, with Stalybridge coming online earlier for Manc commuter services.
The challenge I see really is that this fleet will need to last 30yrs, well past 2050, so will have to be compatible with complete traction decarbonisation

- that's gonna make the DFT squirm!