A time will come when Scotrail will really have to bite the bullet and replace the sprinters - no doubt by the next franchise at least.
I reckon an newly built DMU with end gangways and based primarily on Iarnród Éireann's Class 22000 could serve as a replacement for the entire 156 and 158 fleets on the WHL, FNL and GSWR - Maybe throw in the HML locals into the mix to replace the Sprinters entirely.
Reason being is that it balances up comfort (provides a decent differentiation for commuters and tourists alike) with capacity and general operational efficiency, whilst providing an enhanced service for passengers on all routes operated on. It also doesn't confine certain sub-classes to the one route, unlike what Swiss style tourist coaches do. It allows the 156s to work local routes (until electrified) or go off lease and displaces 158s on the Far North line to enhance capacity elsewhere before succumbing to age and progress of electrification.
In my opinion, an order of such a variant of these units should be (assuming electrification reaches Maryhill, East Kilbride, Barrhead and Kilmarnock):
~10 x 4-car Class [y]/0:
Glasgow to Fort William/Mallaig/Carlisle/Newcastle
Capacity: ~240 (21 First Class, 219 Standard Class)
Shop counter and trolley station (Operated by trolley person after passing through the train initially - doesn't require additional staff)
Single Leaf sliding doors
6 bike spaces
1:2 ratio of bays to airline rows, all aligned with a window, 2 plugs and USBs per row
2 wheelchair spaces
3 toilets (1 wheelchair accessible)
~20 x 3-car Class [y]/1:
Glasgow to Oban/Stranraer/Dumfries
Inverness to Kyle/Wick/Thurso
Capacity: ~180 (All Standard Class)
Trolley station
Single Leaf sliding doors
4 bike spaces
1:2 ratio of bays to airline rows, all aligned with a window, 2 plugs and USBs per row
2 wheelchair spaces
2 toilets (1 wheelchair accessible)
~20 x 2-car Class [y]/2:
Glasgow to Oban/Stranraer/Dumfries
Inverness to Kyle/Wick/Thurso
Capacity: ~150 (All Standard Class)
Trolley station
Single Leaf sliding doors
2 bike spaces
1:4 ratio of bays to airline rows, all aligned with a window, 2 plugs and USBs per row
2 wheelchair spaces
1 toilet (wheelchair accessible)
Aside from the possibly dodgy quantities; for me, the main principle is realistic in my opinion and very reasonable on a number of levels which would see long lasting benefits for at least the next 30 odd years. Crucify away never the less.
Also thought I'd have a go at seeing how an end gangway 22000 would look,
380101 isn't going to be happy with this