Good and bad nationalism

Recently, I read an exchange concerning good and bad nationalism. One commentator expressed the following two sentiments, among others:

(1) "It is not he task of the state to reprogram its population to conform with the state’s values. The opposite is true: the state has to bend itself to the population’s values”

(2)  ”Multiculturalism just plain doesn’t work, and also violates my values…”

This piqued my interest. Personally, I don’t agree with (1) but I understand the position and can sympathize to some degree. My question is what the logical consequences of the combined positions would be.

It seems to me that they lead to a world of insulated states, each inhabited by people who share the same values - not primarily as a consequence of cultural inculcation, but rather by individuals repeatedly choosing to remain / reenter that particular state from some abstract state of nature. If an individual or a minority of citizens in some state feel that they do not fit in, they may either seek out another state and ask admittance (but may be rejected); or they can found a state of their own, if possible.

Is there any cultural drift at all in such a world, either intra- or interstate?

If so, I guess it could also happen that a majority of people within a state at one point feel that they no longer agree with the values of that state. At that stage, the state could either split into two or more new states or - and this seems more plausible to me - work to influence the minority to update, as it were, their values to conform to the majority view.

All of this is compatible with democracy. But it seems unwieldy. Also, I guess it takes some magical thinking to imagine that it leads to the best possible society and outcomes in any one state, not to mention in most or all states. At any rate, global coordination seems hard to achieve, if it is at all desired. (In fact, it may perhaps be described as multiculturalism on a global scale.)

The big question is, of course: What does the ”best” society mean? One approximation is to say that it is the kind of society that fits best with its citizens’ current values. Another is to say that it is a society which caters to everyone’s actual long term interests - even if these seem to contradict some current interests.

Even if you are not an authoritarian rationalist globalist socialist, it seems to me that any functioning democracy (or other society) must involve some kind of (mild) coercion, preferably in the direction of everyone’s long-term best interest. A collection of ”opt-out” states does not seem promote the common good (as I define it). Furthermore, it does not seem practically tenable.