I think HK did a huge disservice to Civ7, compromising civ switching mechanics, despite the implementation being completely different.
Ah yes, even Humankind is to blame... couldn't be a game failing on its own merits.
The mechanic itself has no merit in a 4X game, unless that 4X game was designed exactly like EU or those other grand strategies where you actually play on the real world map, as the real empires.
That's where you might look at it and say, okay I can play as literal Rome and Rome can become something else under certain circumstances which you can SEE and CONTROL.
It doesn't fit in a world where your empire doesn't change, and doesn't mirror the real circumstances which lead to dissolution and evolution of empires.
It leads to logical inconsistencies, like everyone switching empires at once, or a worldwide crisis (under what rare circumstances is a sudden crisis going to hit everyone on earth and dissolve all empires??).
When we first booted up Civ, we accepted one fundamental suspension of belief - yes 'the Americans existed in the Stone Age' - but after that, you continue to play a game that feels rather natural and goes through the processes of the evolution of Empire across history, culminating in a hopefully dramatic end era where you all race towards various objectives and obliterate each other in a climb to be the best.
Now with C7, you have to continuously jerk yourself out of immersion because you're constantly faced with things that make no sense.
Why is Napoleon leading Egypt? Well, to get to France that's why.
The Mongols have no successor, so who are they now? Mughals? So they used to be thundering nomad hordes, and now they're merchants?
Wait and the language changes too? But why are the cities still named in the old language?
The narrative aspect is disrupted but you don't leave space for the gameplay aspect either.
Civilizations pivot their entire gameplay overnight during an 'unseen' period of time.
You get this railroaded experience where you pick the new Civilization and just play out their unique until the end, then switch, and it's essentially musical chairs.
Most of the progress you make is impacted, unless, you happen to make very specific progress to fill out a very specific tree to keep some part of the snowball.
So it's even more railroaded as you design your entire playstyle to fill out this tree to stay in the lead.
Actually Humankind had the same issue with Era Stars.
Stop making players fill very specific trees, or get specific stars, or writing in specific narrative junctions, era switches, civilization switches, stop forcing a narrative on a game
whose entire purpose is to make a narrative out of itself. The game IS the narrative. We don't need the FIRAXIS narrative.
When you win a war against a long-time rival, that's the narrative.
When you steal a Great Person from another Civilization, that's the narrative.
When you edge out your Spaceship just 2 turns before your mate does, that's the narrative.
When you bully the city states and others rise up to defend them, that is the narrative at work.
The better of a sandbox the game is, the better it is at writing its own natural narratives that actually fit what is actually happening in the game.
The more a game adds friction between players, the more interesting stories you can get out of playing a game.
Just keep the game open-ended, with open objectives you can fill in a multitude of ways, with plenty of player interaction, and you will get a winner Civilization, of that I have no doubt.