As someone with many years of flying CX behind me and more recently SQ, I would be horrified at the idea of them being part of IAG.
On all levels quality costs and that is reflected in the crew pay and allowances as much as anything else.
Do remember that Walsh, a disgusting little man who I’ve met several times, earns more a day than a new member of cabin crew at BA earns a year. That is simply immoral and anyone who allows it to happen is quite simply corrupt. While he remains there is no place for IAG expansion in the quality end of the market. Better he gets his mate O’Liary to introduce FR as a feeder airline to BA, people probably won’t notice the difference given how far and low BA have sunk.