Some fair points by EI-BUD though I would pick up on a couple.
While regional flying outside of London isn’t done by BA currently and is something WW got out of in the past, it doesn’t mean they couldn’t or shouldn’t do it now under the right conditions. For example, if routes or a base (I’m thinking the likes of SOU, EXT) are profitable and aren’t so likely to see LCC competition, why not keep them? There is precedent for this within IAG already, for example EIR have some relatively oddball routes out of ORK and SNN to the UK and France and Air Nostrum/IB Regional fly around regional Spanish cities and the Balearics.
You question a lead-in to 2022 for EIR routes but that isn’t too ridiculous. We’re almost in 2019 already with summer ‘19 on sale, pruning would likely occur in 2020 along with back-office integration, further transition in 2021 and you’re there already.