-The French defeated the Prussians at Sedan (Bismark was forced to surrender due to extreme power struggles within the Thule Occult Society that runs Germanic politics), thus no German unification.
-Austria-Hungary and Prussia keep clashing for hegemony in Central Europe; after two wars including liberal use of flying citadels and lighting-powered airships, things stall. Bismark slowly manages to bring the North German Confederation into the Prussian fold.
-Without having to divert forces thanks to the unexpected victory at Sedan, Napoleon III manages to hold up his promise to protect the Pope against Garibaldi. Rome remains under control of the Pontiff and the Italian Unification starts showing cracks. Many conflicts later, mostly engineered by the Austrians and, to a lesser degree, the Venetians, France intervenes and the Peninsula balkanizes again.
-In the ensuing chaos, Naples and Sicily split into two crowns held by the same person and Venice gets overshadowed by a sun-blocking Austro-Hungarian flying fortress yet manages to survive by filling the suit of a French ambassador with dirt brought from Paris and declaring the man Il Blu, having sovereignity upon himself (so long as he wear the dirt-filled suit, of course).
-The Great Powers get involved and demand some compromise regarding the Italian and Sardinian crowns. Kingdom of Lombardia gets fabricated as a result. No one is truly happy with the result.
-Napoleon III, who somehow has survived 11 assassination attempts at this point (pro-tip: He actually gets killed, but Venetian conspirators keep bringing copies of himself from the past and using some bewildering phrenological techniques to make him think he's the same person), deems himself a Chosen One. Asks the Pope to revive the title and regalia of Holy Roman Emperor (abolished by his uncle some decades ago).
-Meanwhile, south German states are in panic at the prospect of Prussian and/or Austro-Hungarian invasion. Events are manipulated in order to convince King Ludwig II of Bavaria to head a unification effort, which the English, Dutch, and Russians have secretly agreed to support.
-Ludwig II declares Restitutio Imperii and brings the Holy Roman Empire back along with Hesse, Wurtemberg, and Baden.
-Problem is, the crown is currently held by Napoleon III. So they solve the matter in the manner of royal gentlement: They bet it on a game of cards.
-Ludwig wins the crown, gets declared Emperor by the Pope. The French and Venetians agree having the Empire back in play will be useful to keep the bigger German powers in check. Other Great Powers are equally happy. Bavarian nationalists are exultant. Ludwig quickly realises he's not ready nor willing to be an Emperor and locks himself up in Neuschweinstein, leaving the the new empire in the hands of some very efficient, yet very sinister, bureaucrats who are now under the payrol of half the continent to push the nation into their spheres of influence. But mostly it's Venetians. It's always Venetians.
-Ottomans discovered alchemical methods for making stuff fly during an expedition into Afghanistan in the late 1700's; theirs were the first flying vessels in Europe, in fact. This allows them to fare much better against internal insurrection, crushing rebels left and right and making the Tanzimat reforms seem -only seem- less urgent.
-The Sultan gives some old skyships to the Berbers so they can hold up against the French. The Barbary Coast never gets pacified, and the pirates are now launching razias as far away as Brazil and India. Everyone unhappy except the Turks, who are cashing in on the headache this brings to competing powers, as well as actually cashing in cash from their loot.
-Skyship Bombardment Policy helps the Ottomans in the short run, but after almost a century, all it's done is push minorities to their limit. Empire's about to collapse from within, and the Janizaries are plotting independence by taking over Rumelia (the Balkans) while the Sultan is busy with the six hundred and fifty seven different revolts he's about to experience.
-A frustrated Prussian populace shouts demands of imperial glory. The Brandenburg Company heads into the distant lands of Mu, Lemuria, and the South Indies, before the East India Company and the VOC gobble up everything. But that's another story for another map.