IMO the #1 problem is not about "cultural differences"', but is a problem between the two persons. One of them seems to forever be the symbol of "AF and KL can never work closer together". I don't think AFKL can afford this situation. Elbers seems to have ended up in a very difficult spot. IMO at this point it does not matter how competent he is.

In my (non-airline) experience cross-cultural company marriages always underestimate the tribal loyalties (its bad enough when two companies in the same country merge TBH)

If everyone goes around still carrying a French or Netherlands flag tattooed on their metaphorical foreheads you'll get nowhere. You have to see it as an opportunity - and the best way is to mix up the workforce as fast as possible IMHO

Not very easy in rigid airline staffing structures

I guess that in those circumstances English would need to be the common language. I suspect that one part of the company would find that unacceptable.

As a group, the ATCOs in France wish for English RT in their airspace exactly the same as the visitors do.

Not really, You are talking about the administrative language or the operational language ? Indeed for many countries, the administrative must be in the language where the airline is located by law . France and Spain for instance still have this rule. Not sure for the Netherlands , but last time I looked ( many moons ago I must admit). the KLM administrative papers were in Dutch... The Lufthansa admin is only in German by the way..
But making the operational language English poses no major problem anymore I would say especially since the pure domestic pilots are long gone and language proficiency tests are now mandatory..
Anyway , first there are ways around it , and secondly rules can always be changed... This is why I look at the Canadian ideas with some interest.. ( and by the way , in Canada they also use 2 languages on the frequency .. .:E )

Well, can't be too bothered about all this. The way that KLM is being treated now by AF is exactly the
same as KLM treated Martinair in the past. A good running carrier being completely plundered by
its parent company. Sounds familiar? Crying foul about this kind of practices by KLM employees is
hypocritical. The French just copied KLM's behaviour. Transavia is another victim by the way.

A small note about KLM's finances: its standalone revenue would never be as high without Air France's
booking system and network. Stand-alone they would be very small indeed.

Very fair comment ATC Watcher, as ever.

I was thinking of the operational language, but at every level of the company. This in response to the suggestion that to truly be a merged company, AF/KL should mix up the workforce. Maybe I'm being unfair, but the French government still have influence within Air France, and I imagine there would be some resistance to English being the operational language within a company seen as a French national champion?

True, but only in Quebec.

Long articles in both le Monde and Figaro newspapers yesterday , looks like Ben has got all what he wanted . in exchange for renewing KLM CEO, he got effective control of KLM by creating a CEO governance that include KLM CEO and AF CEO, the group Financial Director and Ben as chairman. So the articles say Ben gets control over operations, routes, fleet acquisition and strategy for BOTH airlines.
As a (unrelated) bonus he signed a agreement with AF SNPL for a 4% increase ( they wanted 10) and some guarantee for the future of AF , effectively ending all SNPL industrial actions.
Not bad for an outsider ...

I think that the job of CEO must be made a lot easier when your company just reported an yearly operating profit of €1,300,000,000

Love it! Didn't see that one coming.. Fighting fire with fire :E

It seems the Dutch acted, actually not for best AFKL interest, perhaps they thought in favour of KLM "alone", and it seems without much consideration for what happens in the long term. Another possibility, as somebody else said, is that this was briefed and "agreed on" with the French - at the moment I think this is unlikely.

Dutch increase stake in AF / KLM
 

BBC says:-
"France has reacted frostily to the Dutch government's sudden purchase of a 12.7% stake in Air France-KLM in attempt to counter French influence.

Shares in the airline company fell almost 11% after the Netherlands government said late on Tuesday it was acting to protect "Dutch interests".

The Dutch aim to match France's 14.3% stake in the airline.

French Finance Minister Bruno Le Maire insisted the company should be "managed without national public interference".

According to French reports, the government in Paris was informed of the Dutch move only an hour before a press conference on Tuesday night, and after the shares had been bought.

A ministry source told AFP news agency the Dutch move was both "surprising" and "unfriendly", more in the manner of market traders than a state shareholder.

Meanwhile, French President Emmanuel Macron said the Dutch government should "clarify its intentions".

What the Dutch say

"Buying this stake ensures we have a seat at the table," Dutch Finance Minister Wopke Hoekstra said of the move, which cost about €680m (£583m; $774m).

The justification, he said, was to protect Dutch economic interests and jobs - particularly regarding Amsterdam's Schiphol airport. Schiphol is Europe's third busiest airport after London Heathrow and Paris Charles de Gaulle."

It was definitively not agreed , French President Macron talked this evening about an hostile move while the Economy minister Le Maire talks about an unfriendly attack. which took everyone by surprise.
Anyway more State involvement is exactly what the new AF/KL CEO wanted to move away from in France , and now that the Dutch State jumped in , this is unlikely to happen . Result the AF share lost 11% today. Bravo !

Or the Dutch government realised after their meeting with Smith and the turmoil around the reappointment of Elbers that the French state still had a very large influence in the company, regardless of what Smith wants.
And with the French state not reducing their stake, the only option was to buy, if the Dutch wanted to, at least, neutralise the French influence.
It only lost what it had gained in the previous 5 days, most likely a correction and nothing significantly more.