Does one need to be of German extraction to practice TIDE? Not at all. TIDE is from the Mishnah and Gemara.
"Rabban Gamliel the son of Rebbe Yehuda HaNasi says: Beautiful is the study of Torah with derech eretz, for the striving of both makes one forget sin. And all Torah that does not have work accompanying it is ultimately nullified and drags [in] sin. And all those who are involved with the community (engaged in communal work) should be involved for the sake of Heaven. For the merit of their forefathers assists them, and their righteousness stands eternally, and you -- I apportion reward to you as if you had done it (by yourself)." (Pirkei Avos, 2:2)
"Our Rabbis taught: 'And thou shalt gather in thy corn.' What is to be learnt from these words? Since it says, This book of the law shall not depart out of thy mouth, I might think that this injunction is to be taken literally. Therefore it says, ‘And thou shalt gather in thy corn’, which implies that you are to combine the study of them with a worldly occupation. This is the view of R. Ishmael. R. Simeon b. Yohai says: Is that possible? If a man ploughs in the ploughing season, and sows in the sowing season, and reaps in the reaping season, and threshes in the threshing season, and winnows in the season of wind, what is to become of the Torah? No; but when Israel perform the will of the Omnipresent, their work is performed by others, as it says. And strangers shall stand and feed your flocks. etc., and when Israel do not perform the will of the Omnipresent their work is carried out by themselves, as it says, And thou shalt gather in thy corn. Nor is this all, but the work of others also is done by them, as it says. And thou shalt serve thine enemy etc. Said Abaye: Many have followed the advice of Ishmael, and it has worked well; others have followed R. Simeon b. Yohai and it has not been successful." (Berachos 35b, Soncino Translation)
As R' Shimon Schwab explained, “But Rav Hirsch also had behind him a solid mesorah from gadolim who showed him the way. From the time of Chazal through the period of the Geonim; the Rambam, the Chachmei Sepharad through the Talmidei Hagra all the way down to his own Rebbe the Oruch L’ner and his disciples. Rav Hirsch had his mesorah. (Selected Speeches, p. 243)
In my view, every period of Jewish history has had Torah Im Derech Eretz. Even Eastern Europe had its own version. It didn't include involvement in affairs of state (think Jack Lew) because the Czar didn't allow it. But most Jews worked for a living for most of the day. They were not Torah only. Maybe some of the Yeshivot were, but you are talking there about a few hundred people among millions.
Therefore, we must distinguish Hirschian Torah Im Derech Eretz from the others. As Isaac Breuer explained, Torah is eternal. TIDE changes in each era. You can say it changes for each society as well. R' Hirsch laid down a TIDE for the modern Western world. Yes, he did it in Germany, but in my view, his writing speaks to all of Western society. For example, consider the following:
"Derech Eretz includes everything that results from the fact that man's existence, mission and social life is conducted on Earth, using earthly means and conditions. Therefore this term especially describes ways of earning a livelihood and maintaining the social order. It also includes the customs and considerations of etiquette that the social order generates as well as everything concerning humanistic and civil education." (R' Hirsch on Pirkei Avot)
How is that Germany? That could be anywhere. It's quite general.
"He will not be a stranger to anything which is good, true and beautiful in art and in science, in civilization and in learning. He will greet with blessing and joy everything of truth, justice, peace, and the ennobling of man, wherever it be revealed He will hold firmly to this breadth of view in order to fulfill his mission as a Jew and to live up to the function of his Judaism in areas never imagined by his father. He shall dedicate himself with joy to every true advance in civilization and enlightenment. But all this on condition that he be never obliged to sacrifice his Judaism at any new level but rather fulfill it with even greater perfection." R' Samson Raphael Hirsch, 1854, Quoted in Guardians of Our Heritage, p. 290
That would apply to any society that has advances in civilization and enlightenment.
Besides that America is a Germanic country. Aside from the fact that German Americans, some 50 million strong, are the largest ancestral group in the country, the USA was setup by Anglo-Saxons, who themselves descend from Germanic peoples that emigrated to the British Isles in the fifth century. "The Saxons were a confederation of Germanic tribes on the North German Plain, some of whom conquered large parts of Great Britain in the early Middle Ages and formed part of the merged group of Anglo-Saxons that would eventually carve out the first united Kingdom of England." (Wikipedia) Then Angles were likewise a group of Germanic tribes that invaded England. The very name England (and English) gets its name from the Angles. Even British Kings George I and II were born in Germany, spoke German, and belonged to the House of Hanover. English is a Germanic tongue with French frosting on top. It should be no surprise that the British and the Germans have much in common and one sees it in their orderliness, rationalist mindset, ambition, intelligence, and cool demeanor. (I'm not saying that they are unfriendly, but you know what I mean.) So, too, does the American aristocracy that set up the country, laid down its primary culture, and continues to run the place.
Even though my ancestors are from the Ukraine, I am more Western and German than Eastern European as my family left Eastern Europe a century ago. America has many sub-cultures, some not Anglo at all. I can take you to all kinds of neighborhoods in Metro New York City, such as Chinatown in Manhattan, Little India in Jersey City, or Williamsburg in Brooklyn, to demonstrate the point. However, I was raised in the suburbs of New York, and my culture was defined by the public education system which takes it queues from the universities which themselves are Anglo-Saxon in style (picture the archetypal professor in a tweed jacket with elbow patches). So, too, are most corporations Anglo-Germanic in style with their command and control organizational structure.
Nevertheless, America certainly is not 19th century Germany. Even Germany is not 19th century Germany. We are a more casual society, not quite so punctual; although we are punctual. Certainly, we are a law and order society as they were. We are not nearly as classy. Over the last twenty years in particular, the society has become incredibly low class. If it keeps going like this, we will all have to revert to the Eastern European model. But one can still keep his radio tuned into WQXR, the classical music station of the New York Times, which still exists despite a near bankruptcy. One can watch videos of Charles Dickens' Bleak House.
It's not so simple as it was in R' Hirsch's day to take the best of general society without getting polluted. In his day, Dickens was new literature. That's what people were reading. But you can argue that it's even more important to address the outside world because it's nearly impossible to shut the wireless society out. So if you don't engage it proactively, it sneaks up behind you. If you don't know how to think for yourself, you are doomed because you are challenged every day. I see many people who follow the "shut off your brain" model of life getting very badly hurt. You need a nimble mind in this society. You need to understand the society in all its nuances, not just with dogmatic and sweeping condemnations.
Thus, I believe we need an American Torah Im Derech Eretz. Hirsch should be the foundation since he developed a model for the modern world.