What I want to know is, in this circumstance, does Germany still see a revolution and/or democratization? What are the prospects of an elected Chancellorship by 1920?
Certainly no revolution. The 1918 revolution came about due to a special mix of circumstances, a lot of them being removed in this scenario:
- British neutrality means a different situation in the German Fleet (no harbour sitting, more discipline, no planning of the "Schlacht am Kap des Großen Selbstmords" which drove the seamen to mutiny
- Peace in 1917 means no general paralysis of the public and of politicians due to the Spanish flu.
- No defeat.
The system broke down when the Kaiser abdicated. This was a measure to receive easier peace conditions and again due to the defeat.
Seriously, why should the Germans rebel against a victorious system? The victory parade in Berlin will be great!
Also, the unbeaten army will be in a totally different position to deal with insurrections (but I do not expect any).
- No blockade. In your scenario, Britain is neutral. If the French tried to blockade the German coast....good luck.
So this means that the Germans will have suffered shortages, but no hunger. Morale in the general population will be better, besides, your war is probably by 9-15 months shorter than OTL.
Democratization is more difficult to assess. There will be some, but it will be gradual.
- As we saw in other victorious nations during the 20th century, the mobilized masses will want to have their spoils of the victory. They will want more political rights and political reform.
- So, whereas in a peaceful 1910s the Reichstag election of 1917 might have been a setback for an SPD which wouldn't have managed to bring about reforms, the war might push their percentage a bit over 1912 levels.
- In 1917 OTL, Wilhelm II promised to reform the Prussian suffrage. I expect that this reform will come to fruition and will bring about a progressive/SPD/Catholic majority in the Prussian Landtag as well. Now you all know that Germany was (as it is) a federation of Länder in which major political influence lay.
Most other larger Länder had alredy adopted equal universal male suffrage, but Prussia is the Land where more than 60% of all Germans lived.
- The other key aspect is a changed definition of the responsibility of the Chancellor. The German constitution was in a dead-end-street already years before 1914 due to the Wilhelm II usually appointing Reichskanzler without a majority (Bülow had one for a short time).
My guess is that there will be not much of a sudden celebrated change, but that
a) members of the Reichstag will become the usual choice to enter the cabinet or be appointed as Reichskanzler
b) the appointment of a new Kanzler will take the majorities into account and the heads of the parties will be heard beforehands
This is doable without the face-loss of having to change the constitution to placate the political will of the people. This could be done later without much fuss once these new habits have become perceived as the normal political way.
-Ebert might become the first social democrat cabinet member, but there will be no SPD-chancellorship anytime soon, maybe 10 or 15 years after the war. A Kanzler from the ranks of the Fortschrittspartei, or a Catholic would be spectacular enough. This might even be the case if the Reichskanzler is actually elected through the Reichstag (which would require constitutional change).
- Wilhelm IIs influence in the army will have shrunk to very low levels due to his performace during the war. It will be clear that the Kaiser is just a nominal commander in chief. I am not sure about the situation of the Kronprinz to that regards.