To me the 'charisma' that Civ has is not just presentation. It's the uniqueness and variety on the mechanics: ie the UAs/LUAs, the city states, great works. A lot of competitors tend to be a lot more generic plus/minus modifiers (this civ gets +1 from rivers, and this civ +1 from deserts, and this civ +1 to culture, and this civ +1 to science), etc. That's also civ's core, but Civ dresses it up better, makes mechanics that feel more exciting/unique to me. Humankind imho massively had this problem imho, which was surprising since Endless Legend has some fairly distinct factions.
Civ also does peaceful victories much better. Most competitors are basically domination games with some token bucketfill peaceful victory on the side. Civ has a lot more thought into things like the culture victory and the science victory.
I also think there's generally space for multile good 4x games - that just expands the market, since people can buy multiple games. It's not a direct competition. Civs competition is really just itself - if 7 is good, people will buy it, if it's not good, people won't, regardless of what other games are out. I.e. even if Cities Skylines hadn't come out, no one would've been playing SimCity.
Speaking of SimCity, biggest danger with 7, imho, is some sort of 2K directed 'monetization' mechanics that end up ruining the game. Fingers-crossed.