I would be astonished if the North Wales Coast line was not electrified by soon after, if not before, HS2 phase 2 opens. There will be huge political fall-out from the North Wales services remaining on the classic line post HS2 - "why does Scotland get fancy trains when we don't?" sort of thing. There are 2 "spare" half-trains planned into the HS2 timetable, one of which could be an hourly North Wales 200m service if that did happen.
I think the end game of the Civities (all of them) is that they'll end up being the only remaining DMUs and deployed on branch lines, quite possibly significantly derated, geared down to say 50mph and burning some sort of biodiesel and with enhanced exhaust scrubbing fitted. If they were converted to 100% rapeseed biodiesel that's carbon neutral (to the extent anything is), and improved exhaust management tech could result in them literally only kicking out CO2.