I'm really curious on what will happen if we start seeing US coproductions. My country has a local netflix production office and from a friend that works there in general the big streamers with production offices in other countries are very hands off. They pretty much only greenlight stuff, oversee that things dont go against company guidelines, pressure people to stay under budget and pay. Mostly they act as distributors and take advantage of being able to submit things to US awards and press as their own.
I wouldnt want US producers making decisions on international productions tbh because those would probably loose part of their not US identity
Mm, I mean, Netflix wouldn't actually be the US production company for a co-production, anon, because their local offices aren't really producing shows or films (we have one here too), rather they're the equivalent of a network/channel. They commission content - or greenlight stuff, like you said - but they're commissioning that content off an actual production company. Take the Heartbreak High reboot for instance - that's 'a Netflix show', but it's actually being produced by Fremantle Media Australia.
Similarly, Interview with the Vampire is an AMC show (and AMC does have a production stake in it through it's AMC Studios), but it's actually being produced by Gran Via Productions (Mark's company) and Dwight Street Bookclub Productions (Rolin's company - which has a very cool website by the way). They're producing it for AMC, and as a result, a co-production wouldn't be done through the network, it would be done through their companies, via way of an official treatise (of which the US currently doesn't have any, so it's kind of a moot point).
(I actually know a bit about this because my mum is a documentary producer who specialises in co-pros, and the theatre company I work at also does a lot of co-pros, albeit in performance, not screen).
Co-productions can be official or unofficial, and sure, unofficial ones can get very sticky, very fast, but official co-productions - which, from what I read, it sounds like these US producers were interested in - are formalised through government, meaning they're official national treaties with rules that both nations negotiate. This can take years - the Australian-Indian one that recently got ratified certainly has! - but the rules would be real, and those rules are usually highly informed by the production and creative unions in both countries.
That doesn't mean there's a one-size-fits-all approach to them either. Some do function effectively as production service (i.e. it's a Chinese film for instance, but utilises Australian crews, actors, and books a local producer to organise all of that), or it's a full creative collaboration like one of my favourite films, Bright Star, which was an official Australian-UK co-production with Australian filmmakers collaborating with British ones to tell a story.
The point though is an official co-production treaty would protect both parties from being overpowered, because the boundaries of it would literally be government mandated (and government agencies can and do step in), y'know? Also, again, the co-production would be between production companies as opposed to a streamer/network, which does shift the relationship and the power dynamic to one generally (although not always) more collaborative. Most boots-on-the-ground producers are very different from studio executives/producers, and if they were to do an official co-production, producers from both sides (or more! My mum's done three-way-country official co-productions before) would have to want to work together, otherwise they'd go the route of the production service, as opposed to a collaborative co-production, if that makes sense? And sure, it could mean theoretically a government would strongarm another, but then it would literally be a diplomatic incident, which nobody wants.
They're definitely complicated, but honestly, the American industry is big enough that if an American production wanted to be American, it would just be American, or engage a local company on a production-service level. Again, co-production treaties were originally intended to help smaller industries competitive with the US by having them collaborate, the whole point is that the US hasn't needed them.
Just because countries have a co-production treaty too doesn't mean that they will use them. Australia's had a co-production treaty with South Korea for more than a decade now, and there haven't been any co-productions yet. Not for lack of trying though, I will say! A few have almost gotten up - one series actually got so far as to start crewing last year before it fell over - but these things are often slow and require a lot of real collaboration to work. It's kind of baked-in in a lot of ways, and some US producers being interested in them would hopefully be indicative of a desire to do that collaborating, not taking over, because again. They've got the $$ to just make it American if that's what they want to do.