And another thing-what with EGIP happening, where will all of ScotRail's redundant 170s and 158s go?
The first EGIP stage between Edinburgh and Glasgow, should see a maximum of 16 170s made available, however, some of them will be retained for extra capacity. I really doubt SR will let 170s go, although they perhaps could be lent on to release the ex-Hull Trains quartet. Otherwise, I foresee some ex-E&G 170s replacing 158s on the Fife Circle and Dunblane services (until these go electric as well), with some 158s being released (the ex-Wessex/SWT 8?) and perhaps a few 158s might allow a couple of 156s to be displaced, from say the Shotts route.
When Dunblane gets wired, something like another 14-16 units should be released, with my guess being that some/all of the remaining Haymarket 158s (726-741) will get a refurbishment and with the West Highland cleared for the class, will be deployed there to displace 156s. The East Kilbride and Barrhead wiring plans will directly see off a number of 156s directly, with either 158s or 170s used to displace the remaining 156s from the GSW and Stranraer routes, following due route clearance for these classes.
In summary, Scotland to release all 48 156s by the end of the decade, plus possible small numbers of 158s and 170s, more if TFS manage to acquire extra long distance trains for the Highland mainline and Aberdeen, with ex-FGW HSTs (unlikely) or VWC 221s (very possible if WC get any extra new build Pendos or whatever) mentioned.