First casualty , EY will go for sure IAG don't need them?
You would think but I would look at EY as no threat to BA or IAG as a whole and if you remove the booking channel from EI they will just go to EY/EK directly rather than BA etc. EI may just enjoy what revenue they receive from passengers who book via them and I think EI probably benefit more from some T/A connections at DUB. Can't see many logging onto EI.com to book EY flights and don't know of anybody who has.
The UA scenario is an interesting one and the recent announcements such as EWR and possibly using T7 at LAX. Surly UA will need to get the boot when they rejoin OW, can OW refuse EI entry if they don't get rid of them?
Personally I am not a fan of AA and would hub in the US with JetBlue or United only or fly directly from LHR or any Euro hub. I would hate for EI to force passengers onto AA.