In OTL, very strong German fears existed with such an outcome. Moltke the Younger felt intense pressure to welcome a conflict sooner than later during his tenure because of Russia's Great Program and French increases in mobilization potential. If the July 1914 crisis had passed with no conflict and no significant loss of face to AH or Germany (that's a tall order), and no more major squabbles appear until 1917, would German strategy still be rested on Schlieffen's approach, or would it have to change and in what ways? I found some references to possible results of Russia's Great Program in Norman Stone's excellent history of the eastern front, but not sure what the effects would have been on German strategy given such a scenario. Germany was losing prestige in Europe in OTL and smaller nations, like Romania, started looking towards the Entente for their future interests. I suspect that would continue after the July 1914 crisis. In addition, could the Junkers continue the policy of limiting conscription to only half the available population, or could the navy continue with getting huge funding under the weight of Russia completing it's Great Program? What were the potential results of the Great Program for Russia?
Welcome to the board.
The exact POD is always important for a complete analysis, and depending on the POD, often things can go both ways.
You listed no loss of face for A-H and Germany, which to me, means they "won" the Serbia issue. A-H had many ethnic issues, and they have now eliminated one of many problems. With Serbian (read Southern Slav) ambitions crushed, now A-H can deal with Hungary 1917 issue.
As an aside, to give you an example of why the POD matters, look at some of the possible immediate effects:
1) Maybe Bulgaria is larger after getting the Southern Part of Serbia.
2) Serbia may have agreed to all the demands, and A-H has a police force in Serbia. Any Serbian politician who gets out of line is simply arrest by A-H and sent to jail for 20 years.
3) Did Russia lose face after having to back down in its support of Serbia? Or did the Russians find a face saving way from day 1. Losing face in Serbia could easily cause a very, very nasty political crisis in Russia.
4) Maybe Serbia had to give all its heavy weapons to A-H as terms of peace.
5) etc, etc.
Now to what i think you want to know.
Before 1905, Germany had a different plans. So likely at some point before 1920, a different plan is adopted. Most likely is to defend against France, and go against Russia. My guess is that Germany will build a line of heavy fortifications in the 1916 to 1920 are in A-L. A huge amount will depend on who is the next GHQ leader.
France's 3 year conscription was a temporary measure, so France's 1920 active army will be smaller than the 1914 active army.
Germany could have afforded a larger Army, at least two full more armies, maybe more. A scared public may support a much larger army. Two-thirds of the budget was not defense, and France was closer to 1/3. Germany could afford to double the Army's budget, if the public wanted to do it. There were plans to add more trucks to the Army, so perhaps Germany chose more equipment over more men. Germany might have developed motorized infantry, or even armored units give a decade or so. It would be a gradual evolution.
The Junkers had already allowed non-Junker officers in support units. To expand they will have to do this even more. My guess is the Junkers support a better army (motorized, tanks, airplanes) and the population support a larger army (more reserve corp). A lot depends on how the politics play out, and the SPD will want changes in sufferance rules for more military spending or any other kaiser lead program.
Navy funding could go either way. My guess is that it stays at about 2-3 new capital ships per year, so Germany has a much more powerful navy as the pre-dreadnoughts are replaced or moved to support roles.
A-H spent the least on their military, and was also do a modernization program. A-H will have a better equipped army in 1918 than 1914. For example the artillery pieces from the 1880's will be replace by modern guns.
There is also the 50 year expiration of the dual monarchy in 1917. A-H might be destroyed as a single country, or it might come out much stronger.