Some of the Pacers ought to have been cascaded out by the 319s though, and haven't been, so I wonder exactly what the plan is. Both in vehicle count but also total metre-length, the 195s do not fully replace the Pacers, and the 331s basically just replace the existing electric stock, so what's the plan?
As far as I can see, Pacers will very much still be operating after 2020 - unless of course Northern wish to repeat the level of cancellations from May 2018, albeit for different reasons.
Northern have received nearly 50 cascaded DMUs. PRM work should be finished which means Northern should have much better fleet utilisation next year. The full effect of Manchester to Preston electrification has not kicked in since the timetable change because the 319s have had a run of problems meaning DMUs have covered. I think there are limitations caused by inadequate power supply and they will be resolved this summer. 331s will run the Northern Connect Blackpool - Manchester Airport service in addition to replacing EMUs east of the Pennines. The 8 x 769s should hopefully be in service and they have a similar number of seats to 5 pacer coaches.
So to answer your question, Northerns DMU plan has always been overcrowding in 2020, and thats what we are heading for next year, although in slightly better trains.