I had not heard of the Libby (Montana) community before.
But from the description in the article, it is clear they are at the liberalising end of the Amish.
And one thing that almost certainly follows from their liberalisation, is their TFR (Total Fertility Rate) is going to gradually converge with mainstream society – not necessarily with the very low levels associated with the completely secular, but at least with the levels associated with mainstream conservative evangelicalism – modestly above the secular average, a lot lower than the Old Order Amish average.
By contrast, groups at the most conservative end of the Amish–e.g. the Swartzentruber–have a very high TFR, and it seems unlikely it is moderating to any significant degree; and also I'm sure their Pennsylvania Dutch is much healthier as a language.
Comparing Pennsylvania Dutch to Yiddish, I think the fact that Yiddish-speaking Hasidic communities (e.g. Kiryas Joel) use it as a written language, e.g. for their newspapers and community notices, and also a language of instruction in schools, puts Yiddish on a much more secure footing. I wonder why the Amish have never made much effort to write their distinctive language down? As far as I know, there isn't any theological objection, just a cultural habit they've stuck with. (They could keep standard German for their liturgy, just as the Hasidim use Hebrew not Yiddish for theirs.) I wonder if at some point, any of them will realise that investing in their distinctive language would be conducive to their long-term prospects of surviving the forces of assimilation.
Hasidim go to school in Yiddish for up to 12 hours a day through 12 grade and their secular and English education ends in 8th grade and is afterward taught exclusively in Yiddish with a side of Hebrew. After 12th grade many men continue to study Torah and Talmud all day for many years with rabbis doing so all their lives. The Talmud is in Aramaic and Hebrew but instruction, conversation and writing about it is conducted in Yiddish rather than English. Yiddish has orthographies in both the standard Hebrew script where it has a vast literature and is intelligibly romanized in Latin script with good concordance.
By contrast Pennsylvania German has never even had a standard orthography much less a literature. In the past fancy Dutch would read and write in Hochdeutsch (the standard literary German, for their times). Old order Amish education is exclusively in English and they are taught to read and write only in English except for reading the German Luther bible for church (as well as they can; typically most do better with the English side in the King James) and singing the Ausbund in German. Education ends altogether in 8th grade. Days are consumed with farmwork or trade work, chores, family life. Other than the Bible and the Ausbund (which is just a songbook) their religious texts are in English. There are some well-regarded old order Amish authors and journalist's who write books and periodicals in English. Many publications used by the Amish aren’t written by old order Amish but other Amish, Mennonites, and others.
In short there is no opening whatsoever for Pennsylvania German to become a written living literary language. There is a translation of the Bible into Deitsch done by outsiders that pretty much no one asked for and no one uses.