Yes, but that was about a century before... and Friedrich II had to make three wars to keep it.
I'd go for that in a Prussia wank scenario:
1866:
- Prussia keeps German and Czech speaking parts of todays Czechia and Slovakia. The war drags on 2 more months, but after that, AH has lost its reserves. There are some more battles against German states on the side of AH, but they are not really important, even if a few times the states win.
- France has to keep out of the war at that time because it was officially on the Prussian side at the beginning and falling into the back of Prussia wouldn't be considered a good idea in view of any future allieances.
- Russia isn't really bothered by that tiny speck of land in Europe, and it's also pissed at AH.
- GB is more annoyed, but it helped prop up Prussia just because it wanted Prussia to counter AH - no short term problems there.
1867:
- Prussia helps to dismantle the remains of AH by supporting independence movements, Serb resistance, and so on. Russia does the same. AH falls apart into Austria and Hungary.
1868:
- France finally has had enough and starts a war against Prussia without requiring any (further) Prussian provocation. As IOTL, it is caught completely off guard by modern warfare tactics, looses lots of ground, but thanks to the battles happening in Germany, the French emperor isn't caught. When Prussian troops, together with troops from southern German states, cross the Rhine, France agrees to peace. Unlike OTL, because the war is won with more losses, there's only little compensation and no change of territory (except maybe Germany gets an unimportant isle in the southern Atlantik or the likes). Germany unites as IOTL 3 years later.
- The war is seen as being unjust by Austrians, too, while the French were advancing, thus creating positive feelings for Germany. Therefore, after the war, Austria is ready to take a limited role in the German free trade zone. It is not ready for further unification, though, despite some popular pressure.
- Italy voices *strong* opinions against any moves of Austrian and German unification, thus unintentionally strengthening that movement.
1870:
(wankfest part, as such moves may be unlikely)
- Prussia is broken up into 5 or 6 independent states, other states are increased in size. A reform similar to what happened later under the fascists, and which should have happened much earlier, considering the harm done by Prussia dominating Germany too much. The German Emperor agrees because he still stays King of the largest state and he can make some people of his choices Princes of the other states, thus strengthening his (fragile) hold of the country.
- Prussia feels the danger of isolation earlier (while a competent Bismarck is still active) and does more to avoid that - arms reductions, naval treaties, alliances, trade agreements... That becomes a model for later politics, thus Germany doesn't get as isolated as IOTL.
- Czechs are given more rights to self determination, local language is used officially, and so on. Poles get a similar treatment. Germany turns "multicultural" while not really abandoning melting pot policies.
1872:
- Thanks to the reforms, and by agreeing on further reforms, Austria, including Slovenia, among others, takes the free trade agreement a step further to join in a military and other agreements. Steps are made to turn Germany into a federation of pretty equal states, so that Austria doesn't mind more and more integration.
- Italy is getting pissed of. But as it knows it doesn't have a chance, it doesn't start a war.
- Russia is still not bothered. It would be to them like Luxembourg joining Belgium would be to Germany.
- Britain is bothered, but can't find much against two countries deciding on their own to get closer together.
- France is pissed, but not enough to try another war, just 4 years after having lost in a similar situation.
- Germany, to avoid isolation, opens its ressource and other markets more to other countries like France, Britain, and so on. The economy profits from it.
The rest is open - don't have too much of a clue what would come. Maybe earlier colonial politics with slightly less ellbow tactics, or whatever.
It is pretty much "what could be" thinking, instead of simulating outcomes as realistically as possible. But on the other hand, more unlikely things happened against all odds...