That's the challenge. The more I hear about Italian history, the more it sounds like the development differential between north and south Italy isn't as old as I once thought and that much of southern Italy/Sicily's relative poverty, and troubled relationship with official law and order, can be more be traced to more recent roots since the founding of the Kingdom of Italy by Piedmontese who bent the structures of the Kingdom to serve their interests first.
Resentment, disorder, and brigandage were apparently common in southern Italy in the early decades of the Kingdom, what internal or external circumstances, if any, could create an opportunity for the ex-Kingdom of Naples/Two Sicilies, or just the island of Sicily, to declare independence, win it, and keep it? What happens to European politics and the fractions of Italy afterward?
I'll get to the question itself in a second, but one thing to note is that the main reason for this is that prior to the 1500s, all of Europe was pretty much an intellectual and technological backwater. That changed starting with the Renaissance (which had its heart in northern Italy) and then the Industrial Revolution kicked off, which made the disparities even more pronounced.
Northern Italy consisted primarily of independent states much closer to the action, bordering France and Germany (the region, I mean). Southern Italy wasn't. Combining the fact that with the rise of the Renaissance and the Age of Exploration and colonialism, the Mediterranean went from being the center of the Western world (relatively speaking) to being on the periphery. And the Papal States were not exactly known for economic/industrial progress (it wasn't until the revolutions of 1848 that things *started* to change), so it was partly responsible for progress not filtering down to the Mezzogiorno.
The other problem was that the region had been under the control of the Spanish (who were themselves out of the loop on progress, and also far more interested in exploiting the resources of the New World). So it was a whole host of factors leading to them getting the short end of the stick. Since the Med was a dead end in maritime terms until the 1880s (and by this time Italy was far more interested in investing in its heartland), they got and to some degree are still getting the short end of the stick in terms of development.
Anyway...
In order for them to remain viable, the Papal States would need to exist as a buffer so nobody (*cough* Austria *cough*) tries to do an invasion. While the two of them being unified (as the OG Kingdom of Sicily was under the Normans) would give them more resources to work with, it also would likely worry the British, since a unified Sicily would need a navy at least capable of controlling the Strait of Messina and being able to exert local control. Even a friendly Sicily would be a concern for the British, given that they're astride the quickest route to India.
Now, assuming the British DO give their approval (even tacitly) to keeping an independent Sicily, that gives the latter a boost as an entrepot (since with Suez trade between Western Europe and Asia is once again going mainly through the Med), and they can industrialize, but at the same time I'd be willing to bet that the Mezzogiorno lags behind Sicily proper given that the former is an island and so can do the Wooden Wall bit to protect itself.
So, yes, *in theory* it could work, but it relies on both the British being willing to cut Sicily some slack (not a given when it comes to naval issues) and the Austrians not being idiots, which as
@Buba rightly notes means relying on Franz Josef not being his inbred dumbass self...so in all honesty it's probably never going to work.
My wet dream would be #1 with Savoyards banished to Sardinia (the island), the Piemont going to a cadet branch/somebody, Parma/Modena/Tuscana/Republic of Genoa etc. reestablished, and a KoI in 1859+Veneto borders (minus Sardinia the Island Kingdom) set up as a federation of monarchies like the Norddeutscherbund, with the dude in Milan being Re d'Italia&Duce Supremo.
But that'd need an SI, I guess
I would definitely read that, although I'd cut the Savoyards *some* slack and let them hold onto Sardinia. If Genoa and the others are independent there's fuck all they can really do without having everyone else giving them The Look if they get a visit from the Good Idea Fairy.
Might a Venetian independent buffer state, a Duchy, Princedom, Kingdom, Serene Republic, be an alternative. Would such a thing have local support and be counted on to not just "give itself" back to the Kingdom of Italy at the first opportunity? Veneto-Friuli had a proud local history and tradition, but I have never heard of it having the bitter experiences of the Mezzogiorno and Sicily.
It's been a while but IIRC the problem was that, being right next to the Austrian heartland, if they tried stepping out of line (and I'm pretty sure there were a couple local rebellions) the empire could roll in to suppress any uprisings fairly easily. It took Prussia smacking FJ around like the cretin he was to convince the latter to let go of Lombardy, the Veneto, and Friuli.
Even if there isn't a unified Italy in this timeline, it certainly would be to Prussia's benefit to pry the region away from Austria. And it may be that Lombardy and the Veneto split apart as well, with independence guaranteed by treaty. Granted Venice would still be screwed on account of having pretty much nothing but being a tourist attraction at this point going for it (though package tours DID exist at this point in time). Be interesting to see how things would play out.
Edited for formatting. This fucking phone...
