A general premise: Italy and Germany are going to have a very similar evolution of their political systems, and those are going to be pretty much in flux for the next two decades or so. However, we may expect them to evolve towards a rather stable two-three party system in the medium term.
Industrialization, the gradual spread of economic affluence among the middle and lower middle classes and end of abject poverty among the worker classes, the entrenchment of the Old Catholics hegemony on the Catholic masses, and their evolution towards a liberal-progressive worldview, are going to favor the emergence of a political system not unlike the Anglo-Saxon one. Say a economically conservative-nationalist center of right big tent party or coalition of parties, a economically liberal-progressist center of left big tent party of coalition of parties, and perhaps a centrist liberal-moderate medium party or coalition of parties.
Progressist Protestants (in Germany) and Old Catholics, left-wing liberals, moderate republicans and social reformers are going to occupy the place in the political system that was occupied by marxist socialists (which shall be marginalized in a far left fringe), and build a movement kinda like British Labor or American Progressists. Conservative Protestants and OC, right-wing liberals and nationalists, and most of the conservative old elites are going to join and form a movement kinda like Britsh Tories or American Republicans (without the fundamentalism, of course). Such movements could either become "big tent" parties, or coalition of parties. A centrist moderate liberal-conservative party or coalition may or may not form among the two big ones. The marxist-socialist far left and the reactionary far right are going to take shape as well, but they shall mostly remain marginalized at the fringes of the political system.
Although this political system is only going to take shape during and after the stay in office of the di Castagna-Barletto-Bismarck generation, they could be supported by and ideally belong to this aborning "Tory" movement: Barletto would belong in its far-right fringe, Bismarck (despite its own strong conservative leanings, out of his political pragmatism) in the center or right mainstream, di Castagna as well or leaning towards its progressist fringe.