True. On the other hand, let's take UI as an example because UI mods are by far the most prevalent for Civ 6, both because there is no DLL source so we are limited to the little we can mod, most of it the UI, but also because the UI in Civ 6 is, to say the least, lacking. The irony of this is that I expect HK to be a master class in UI, given the proven record of Amplitude games in this regard. Thus, if that holds true, there will not be a high demand nor need for UI mods if at all.
In other words, moddability is certainly a big factor, but sometimes the lack of mods or demand for them in an area can mean that the area is well served.
About brand loyalty... well, many of us have been with Civ for its entire lifetime, and that is why we care a lot, including harsh criticism. That's why we mod, that's why we complain here about the things that we find wrong, and that is why we root for competition, because it is the most powerful force to make products, and companies, change direction if the one that they selected is not "optimal" (in quotes because it is a very hard and dynamic concept). That is why I want HK to succeed, because I like the direction they are going, I like some of the systems in their games (namely combat), but most of all, because I like the Civ genre and 4X historical strategy gaming, and I want it to survive and succeed as such, be it Civ or whoever takes the throne, if any. Or all of them.