These 230's can replace the Pacers, as its well and truly is like for like replacements. Then with whatever gap is left fill them with the class 195's / 331's.
It looks good to me.
It can feel a bit like Groundhog Day on this thread sometimes, sooner or later it gets back to the "Why can't Northern take them to replace the Pacers?". Well as already recently said, the Pacers are getting replaced but it isn't like for like. The 195s & 331s aren't stop-gaps, they are band new, higher specced trains many of which will be delivering higher quality services along existing and new routes. The 150/155/156/170s that they have and will receive will mainly be used to retire the 142/144s, although I wouldn't be suprised to see a handful of 144s retained either for short routes where the toilets are locked out, or if they retain some regular purpose have DDA conversions to bring them up to minimum spec.
I'm sure Arriva looked at the 230 option, and I'm sure that if they really thought that they were the answer to all their problems they would have tried hard to convince DfT. But they didn't, and now somewhere in Spain the CAF employees are either finishing off the designs or actually starting to build the first of Northern's new units. Shooter & VivaRail took a punt that the Northern franchise winner would be desperate for a cheap 'n' cheerful, they didn't. And it shouldn't be a surprise really, they are investing heavily in new bus stock across their networks to improve their image, so it seems logical to start to do the same with their new rail franchise.
Maybe the 230s will find a home elsewhere, maybe. Despite all of VivaRails bravado there still isn't a single firm order that any of us are aware of. And they have still to fully prove the viability of their single operational unit, and more importantly convince those in the industry that a re-tractioned, partly refurbished 35 year old unit can outperform younger or new stock.