I think your idea of what your dcs will do as teenagers is very strongly skewed by that blog.
My dcs are British and French. They have never lived in France but are fluent in French, we speak French all the time and considere themselves French as well as British.
I'm not sure that they consider France to be 'their' country, whatever that might mean, but they are French too.
Is it always easy to acheive that? Nope it's hard work and requires a lot of investment, time and financial and effort wise.
But then, if your DH was saying he feels bad that his dcs don't feel Norwegian too, would you accept that and would you help him ensure they do feel Norwegian too? By learning the language, ensuring that they can read in Norwegian, watch program from there etc etc??
The divorce thing sends alarm bells for me. I wouldn't go anywhere with that sort of threats going on. No point talking about a timeline, going back in two years if you haven't settled etc... he won't listen and will go for a divorce. Even if just now, he says he didn't quite mean it.
But I have to say, I think there is a lot you can do to make your own DH feel at home in the U.K., make feel like he isn't completely cut ut of his own family etc... At the moment, it's all about you, the dcs being British being the most important with very little about how yu canalso ensure they feel Norwegian too, they speak the language etc...
I say that as an eu citizen in the U.K. I'm in the same place than your DH and my DH will NOT move to my country.
There is no way that w Utd be workable if he wasn't supportive of me raising our dcs as half British, half French. Supportive of them speaking French at home (and that means often him not following the conversation because in 14 years he still hasn't made the effort to learn French...). Supportive of us going back to France on a regular basis etc etc.
To make a successful marriage with a bi national relationship, everyone needs to make an effort and I haven't hear anything like this from you, bar going back once or twice a year to his family and hating it :(