Thanks for the detailed comments. Lots of stuff to think about.
On Governors, no worries you’re not a fan of my suggestions. But the more I’ve thought about, the more I think Governors are not only a hugely under-utilised mechanic, but are also a big part of the late game malaise. Governors already have powerful “late game” promotions, but this just doesn’t do enough to keep them relevant.
I think the core issues with Governors are variety and being unable to “level” the Governor technology. The first point is obvious - you get the same seven governors, every game, for every Civ, from turn one. The only exceptions are Ottomans and now sort of Secret Societies. Just having more Governors would help this, eg more Civs with Unique Governors. I think Secret Societies will add some variety here, so this aspect may get a bit better.
The second point about “levelling up” is a bit trickier. A core game loop of Civ is unlocking upgrades to things, be it buildings, units, whatever. Governors sort of level up in that they have promotions and get more titles, and you get more Policy Cards that manipulate them. But I think they still lack a more definitive “levelling up” moment that you can only get by having additional Governors that are only available later in the game. I sort of see it the same a Governments - as the game progresses, your Government improves incrementally by you getting access to more powerful Policy Cards; but at various points, you get a big jump in power by unlocking more advanced Governments. I think Governors need the same dynamic, where in addition to your Governors getting better through promotions and policy cards, you also at certain point can unlock and access more powerful (or at least different) Governors.
On Governments and Ideological Pressure, I think that in addition to unlocking better stuff throughout the game (eg better buildings, better units), there are various points where you unlock truly game changing new mechanics or abilities. Examples are unlocking Tier 1 Governments, unlocking Feudalism, and unlocking Industrial Technology (Shipyards, Coal Plants and Power). I think the late game would be improved by making unlocking Ideologies being a bigger deal. Some ways to achieve that would be having T3 and T4 Governments give you access to new Governors (as described above), unique Wonders (Pentagon? Prora? Kremlin?), unique Units and unique Buildings ie in addition to the unique Policies the Governments already let you access.
Unlocking “Ideological Pressure” would be part of this. But I really just see this as an add on to loyalty. Something like you exert additional loyalty pressure v Civs with different Ideological Governments based on your relative loyalty. You could then maybe add to that some Governor Abilities and or Policy Cards that increase or decrease this additional loyalty pressure. And, of course, you’d still have access to all the existing Tourism Wonders and Policy Cards which would now not only impact tourism but would also via tourism have more impact on Loyalty.
On Barbs, I think I’d just be happy with Barbs having a few more unique units. On reflection, I don’t think they really need a whole separate city Mechanic. I’m also not too worried about Vassals etc. I think Colonial Cities need to be more worthwhile - at present, they’re just not worth the effort to found because they just give you more yields when you already have more than enough yields - is Colonial Cities need some sort of more niche or unique benefit. Having Vassals wouldn’t really address this. I think Vassals are more about just having another way to hold cities that don’t require as much micro management and doesn’t entirely integrate them into your empire, ie so the map isn’t just a sea of one colour. It’s not really a big deal because ultimately you can just queue projects for Cities you don’t want to micro, so it’s not like the burden is really that big anyway. Still, having something like Vassals might be a small fun addition to the game.
Anyway. I thought I’d just explain my thinking a bit more, in case you or anyone was interested. No problem if you’re still unconvinced about more Governors and or Ideological Pressure.