I can't believe we are arguing about this already, and saying it'll be a bad thing
Okay, a few facts. Based on *current* service provision, the Lancashire electrification will release about 30 DMUs. Half of these are Transpennine (Manchester Airport - Blackpool North/ Glasgow/ Edinburgh), half of these are Northern...
...of the Northern ones there are two 180s used each day, but the rest are mainly individual Pacers/ individual 150/156s. There are a couple of Pacers coupled to Sprinters, and a couple of doubled Pacers, but really not *that* large a proportion.
Bear in mind that a Pacer coach is about fifteen (?) metres, compared to the normal twenty/twenty three metre coaches for other units, and you have a significant increase in capacity.
Also, its worth remembering that the sucessful Shipley electrification was initially with cascaded units from the London area (the 308s), then replaced with new three car EMUs, then extended to four car EMUs (when the 333s had an additional carriage inserted). There's nothing "set in stone" here.
Also, the age of the 319s isn't a major issue. EMUs are designed to last a lot lot longer than DMUs - there are fewer working parts to "age" for a start.
I can't see any reason for complaining about what will be a massive increase in capacity. Look at the line through Manchester Oxford Road/ Deansgate. Dozens of services and almost all are three coaches or shorter. A real waste of capacity.