Eurofed
Banned
This makes me wonder greatly about how Bismarck might choose to govern in any Großdeutschland scenario where he is in power. Aside from adding more Catholics and minorities into the mix of the Second Reich, The acquisition of Austria and Bohemia would certainly empower his Liberal opposition who might a lot in common with the German Liberals of the former Austro-Hungarian Empire. Hell, the National Liberals might find a lot of ground with them, too, even though they were rather pro-Bismarck.
At least in OTL, Bismarck's counterpart in Austria, Taaffe, ended up scrapping the German Liberals from his cabinet and maintained a rather long ministry from 1879 to 1893 (a surprise, since like the Third Republic, Austrian governments were not known for the longevity) through an alliance with the clericals and Slavic Nationalists (primarily the Poles and Czechs).
Bismarck certainly wouldn't pursue Kulturkampf in any Großdeutschland scenario. Certainly he'd co-opt political Catholicism into alliance? He was the master of realpolitik, after all.
This is a definite possibility. Another interesting butterfly is the Pope fleeing to France when Italy occupies Rome, and taking an explicit anti-German-Italian stance during the Vatican I council. This may cause the Old Catholic schism, that occurred in reaction to the proclamation of papal infallibility during that council, to gain critical mass and the allegiance of the German and Italian Catholics. This would occur because Germans and Italians embrace the Old Catholic Church as a show of patriotic allegiance against a Pope openly hostile to their nations, and thanks to government support for the new Church (a different version of Kulturkampf and the anticlerical policies of the liberal Italian governments). The combination of grassroots nationalism and government support is a mix that can quickly overturn the confessional allegiance of a nation (see the Anglican schism). It may or may not happen, but if it does, it would neatly solve most of the difficulties Germany and Italy (and the Junkers) had with political Catholicism.