If only you could count on _that_ (spoken as a BA member who most definitely can't count on BA for things like operating vouchers are per rules as an example)

Maybe there's been a slight decline in the last 15 or so years that I've been OWE, but overall I think that the value of it has held up pretty well. I would compare it to my Marriott Lifetime Platinum which has really lost in value in that time.

The First Lounge network is a great perk, even if my home BA lounge (which I'm in now) has plummeted precipitously in quality. First check-ins like in HND/ NRT/ LHR are really nice. And sometimes you do get the occasional bit of special treatment on board - rarely with BA nowadays despite me being one of their elites, but CX and MH can often surprise with a special welcome.

That’s only true to a point. The revenue sharing agreements are a union in that they protect and enrich the airline. They don’t help passengers!

What does Emerald get me that I value? First class checkin. First class lounges. Mileage multiplier. Priority boarding.

Which ones do I not care about? Fast track security (I don't need it much as most of the airports I fly through have Clear and I have PreCheck). I don't care about the additional baggage allowance, I never check bags.

Depends what you mean by revenue sharing, all OW members pay into the OW alliance, maybe pro rata to revenue or profit but it's not as deep a relationship as the Atlantic Joint Business between BA AA IB EI AY.

Maybe OW should have an alliance standard that emeralds should get priority customer service on any airline, they already do at airports, but it will be hard to implement. You still have to call into the pleb line and declare you are emerald. Or they can implement call patching through, you call your own airline and they patch over to the concerned airlines elite call center. I can see the line just dropping. Or there are no available English agents. Speaking for IB and CX, the best agents only speak the local language.

As for booking fees, not going to be an alliance benefit and IMO I would not welcome it. Fare rules are fare rules.

The lack of information or colour on boarding passes when you are Emerald with another one world carrier colour, led to me being subject to the sniffy “ oh your flying business class” when trying to access First wing yesterday!

Your BA BP doesn't say emerald?

Not on the phone. You get a white BP with no detail. It simply says business and has group 1. It does not show status nor you FF number. Those details are imbedded in the QR code so it needs to be scanned but some agents make assumptions before doing so.

if you have a BA gold card the BP is gold colour with same level of detail

"Here's my emerald (virtual) card, thank you"

Yes, this has become more frustrating recently for AA flyers, as the elite customer pass-through feature of the AA phone system no longer connects to an elite desk at BA. Used to be so easy to make changes or deal with problems on 125 tickets, but sadly no more. As a result, I try to book my BA flights as AA codeshares as much as possible, because then it's much easier to make changes or resolve problems.

Maybe the feature still works for AY or JL? Haven't tried recently…