I would support PSDs being rolled out in areas with metro-style frequency and usage. E.g. Thameslink, Merseyrail, Leeds Suburban and Birmingham Cross-City lines. Those that aren't already could then be moved to DOO for good measure. I don't think PSDs would ever be justified on rural routes like the S&C and West highland with frequencies at 1tph or below.
I can’t honestly think of a single route on the Leeds suburban network where it would be remotely possible as no route has a single stock type allocated to it.
Most diesel routes are a mix of any of 150, 155 (occasionally), 158, 170, 185 & 195. The electric routes even inter-mingle with other traffic with the exception of the Ilkley line and I’m fairly certain that 331 and 333 doors will not both line up in the same place with PEDs. Also many suburban services on certain routes mix with other stock types including 800/801/802 (Wakefield W, Huddersfield, Dewsbury, Garforth, Cross Gates, Shipley, Keighley, Skipton, Bradford FS, Horsforth, Harrogate). 91+mkIV (Wakefield W, Skipton, Keighley, Shipley). 68+mkV stock (Huddersfield, Dewsbury, Garforth). Class 180 (Bradford I, Low Moor, Halifax, Brighouse, Mirfield, Wakefield K, Pontefract M).
Then throw into the mix Leeds station itself and other stations connected to the commuter network such as Selby, York and Doncaster and you can see that it would be a non starter for Leeds suburban.
The only routes that could ever be conceivably considered for this are ones such as Merseyrail & Tyne & Wear Metro.
I don’t honestly know what the OP thinks is even remotely practical about this idea unless they themselves are going to finance it with a spare £50bn they have (complete guess on that price and it’s probably well north of that cost). This is the sort of knee jerk, hair brained idea the government would come up with then very quickly retract when they realised how much it would cost and how completely unrealistic a proposition it would be. Mind you with this current government…………..