Reading through the notes on the Q&A with the Il2 lead producer (haven't managed to listen to the three hour recording, yet), I'm getting the impression that Il2 is very, very niche and the "777 Studios" appears, maybe as a result, very small. Even their webpage has hardly any material on them. No official address of offices, addresses for applications, showroom of their products etc..
I'm getting the impression that this is a very small number of enthusiasts, probably not even working in a common office, slowly laboring away at a TODO list in terms of things to fix/additions, which they have no hope of tackling in a comprehensive manner without a susbtantial influx of cash (read: broader success of Il2). Provided I'm not completely off with this impression, it's impressive what they've achieved with the new Il2 series and what they are still trying to achieve. But it also tones down expactations.
For comparsion: War Thunder may not be a hardcore Sim, although it's still very sim-ish. But due to its broader appeal, it's been successful enough to allow Gajin to now implement controllable crafts of 7 (?) nations, in the air, on the ground and soon on the water, including respective game modes. Even though each War Thunder plane is far less complex in its behaviour and therefore probably far quicker finished, the pace at which they're able to release notable updates is staggering in comparison. That's not to say Il2 should become like WT, but it offers a perspective between a firmly niche product and something that's comparativley mainstream.
Edit: Also, if the impression of their small size is accurate, any delays of the "Battle of Bodenplatte", "Flying Circus" and "Tank Crew" won't surprise me. Just as in that context, postponing a pacific theatre addon they can't get out in a timely manner due to being stuck with research etc. in favor of more "canonical" addons, seems like a completely rational and necessary decision.
A couple of points:
They aren't a 'small number of enthusiasts', they are a team of qualified professional developers, working out of an office, like any other software company. Yes, the team is small. And yes, they are enthusiastic about their product: which is a good thing.
As for delays, if there is one thing that distinguishes this team from game developers in general it is their ability to release things on time, or at least without the months or years of delays which have become so common within the gaming industry. I see no particular reason to assume they won't keep to this standard.