Switserland had its own seperate national identity far before Germany existed. Far before German nationalism existed and even before the German identity existed. The Swiss identity, seperate from the HRE existed even before they became independent after the treat of Westphalia. The treaty of Westphalia only accepted asituation that already existed. The Swiss were no longer interested in being part of the HRE or a greater German nation. They were already Swiss. Why did people spoke about German Swiss, well simply to distinguish them from the French and Italian speaking Swiss. Not to identify them as German. One thing to realise is that the word for German at its core does not mean German. In English it points towards the Germanic heritage that the Swiss and Germans share with the Scandinavians and the English. In German (and Dutch) it points towards the people. Deutch, Dutch, Diets even Teutonic spimply means people, mainly as opposed to the Latin of the church. Calling a German speaking Swiss would simply mean a Swiss that spoke a Germanic language. Not a Swiss with a German identity.
This discussion simply points to the fact that people on this forum (and everywhere) have a very simplistic worldview.They see someone speaking German and they assume that he must be German. Especialy in history. The thing is: the world is more complexthan that. As I said, noone would claim Americans are English, simply because they speak English. Oreven claim that the Irish are English simply because they speak English. The German national identity developed in the late 18th early 19th century. The Swiss (and Dutch) national identity were already firmly developed in those days. The Dutch and Swiss (and Flemish) did not consider themselves German, simply because they considered themselves Dutch and Swiss. This as opposed to the Austrians (and in a lesser case the Luxemburgians). They had no seperate national identity,so they could consider themselves German when German nationalism arose. Before that time there was realy no such thing as a German identity, nor did people care about it. That is why Prussia conquered so much of Poland and Austria conquered Hungary. That is why Francophone areas like Lorraine and Wallonia were part of the HRE, or Czechia. Nobody was interested in creating a German state. Land on its own (and the people living on it) were key. Not some strange non existing identity.
I'm aware of all these things. What I disagree with is your assumption that a Swiss national identity existed that far back. Much like in the rest of the German lands (best way to describe it, I guess) we are talking here of a
political identity. Loosely confederated cantons, culturally differeing from one another.
My point is that 1800 or thereabouts is the best time, perhaps, to end that political identity. Switzerland was invaded by France, had its political structure altered dramatically, had its borders altered... My scenario tentatively posits that Napoleon annexes the French parts to France, the Italian regions go to the Kingdom of Italy, while the German areas go to the West German Confederation-- which is a hypothetical alternative to the Confederation of the Rhine, basically.
If that happened, barring a defeat of Napoleon and an eforced return to old borders, it would not take long for the former Swiss areas to become fully part of the (West) German nation. Simply because before Napoleon, there was no fixed German national identity,
nor a fixed Swiss national identity. These were political identities, and that's not the same (as you note, in fact).
That's the ATL scenario, and concerns that fact that Swiss national identiy wasn't a well-defined thing by then. Talking about the present day, I understand that identities have become more fixed. Yet - although this is anecdotal - in my own experience, many people in the German countries and regions that are not part of Germany will still consider themselves culturally German. Sure, an Austrian is an Austrian, but Austria is a German country. So is Liechtenstein. And while not countries but regions, so are German Switzerland and South Tyrol.
The fact that the inhabitants of Germany, German Switzerland, Austria, South Tyrol and Liechtenstein live in different countries is, to me, a mere matter of politics. In a political sense, they are not all 'Germans'. But in a cultural sense, they certainly are. They share more than just language, and in fact, when you look at cultural customs, people in south-western Germany have a
lot more in common with their fellow descendants of the
same Alemanni than they do with historically Low German-speaking folk in northern Germany. In the same way, Bavaria and Austria are more alike in countless ways than Bavaria and Berlin will ever be.
So I'm not saying that the German people in Switzerland are the same German people as we find in Schleswig-Holstein... but the German people in Bavaria are
also not the same German people as we find in Schleswig-Holstein. I think the political borders are largely irrelevant to deciding what is culturally German, and that the idea of 'German identity' is internally a lot more diverse than you appear to allow for.
Even if the vast majority of the inhabitants of Austria, and Liechtenstein, and South Tyrol and German Switzerland have no interest in joining Germany politically[1], in my experience (which, if I may say so, is not exactly inconsiderable) a
lot of those inhabitants nevertheless feel that they are members of a
German people. Not
the German people, perhaps, because of the aformentioned internal diversity, but certainly
a German people.
This is not something I have often experienced in the Netherlands, or in Flanders, or in Luxemburg. Those are Germanic nations, but not
German nations. Unlike the ones I discussed above.
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[1] Well, except South Tyrol, perhaps. I've heard a lot of people there argue that they'd love for their region to join Germany. Not Austria.
Germany. Preferably along with the rest of Tyrol.