The growing strength of France alarmed the Germans and Austro-Hungarian Empire who found themselves all but surrounded in Europe whilst Belgium was leaning heavily towards the French. The military strength of Russia, Italy and a rearming France dwarfed the German/Austro-Hungarian's available strength. In the German Parliament the bill to build more warships was killed in the Reichstag much to the anger of the Kaiser in the light of the growing threat on the ground along Germany's borders and the surface fleet was assumed to be strong enough to defend the German coastline as well as defeat any enemy on the high seas.
That strikes me as entirely possible.
Larger armed forces budgets in France and Italy would alarm both Germany and Austria-Hungary. The "weakness" of Russia in OTL wasn´t that well understood. And without the Russian-Japanese war of OTL I suspect the Russian military reforms won´t happen or will happen slower here.
So Russia won´t be as strong as it looks from the outside. But taken together, the threat of France, Russia and Italy allied will certainly result in actions.
(Definitely a larger German army. That´s the easy part because Germany didn´t draft every eligible young man. I seem to remember only 50-60%? And had only a 2 year draft compared to 3 years in France.)
Belgium leaning towards France in the 1900s is the reality in OTL too. That changed slowly after 1910 when alarmed French diplomats in Belgium noticed closer Belgian-German relations. And more and more German influence in Brussels.
I suspect the same would happen here too especially with an Anglo-German alliance. So Belgium will try to stay neutral in a war.
To calm the Kaiser who still wanted his fleet, the planning of what would become the Nassau class Dreadnought was begun. The Kaiser also swallowed his pride and bite his tongue, asking his diplomats to begin talks with the English regarding an alliance. One which the British Government was all too willing to enter into. German ministers had to keep the Kaiser from saying anything inappropriate during the negotiations conducted at his behalf whilst he 'holidayed' in the Norwegian Fjords aboard the Royal Yacht and were for the most part, successful, although his more bombastic statements about French threats to Germany's borders were eagerly lapped up by the press at home and abroad.
In March of 1909 the Triple Alliance was declared in Paris between France, Italy and Russia whilst at the Treaty of Greenwich in 1910 the so called Three Empires Alliance of England, Germany and Austro-Hungary was signed by the King, Kaiser and Archduke Franz Ferdinand of Austria.
Strikes me as realistic too.
British support for the Japanese here resulted in cooler relations with France. Now a France heavily influenced by the military and furiously re-arming will be seen as a threat again. Russia was always seen as a potential threat. And adding Italy to it threatens the British position in the Mediterranean.
The British won´t be happy about that.
They probably would follow long-standing policies by siding with the weaker alliance, seen here as Germany / Austria-Hungary.
(Especially with Germany limiting its naval programs.)
Tension rose in Europe from 1910 to 1916 with both alliances working to improve and enlarge their militaries whilst over the Atlantic the American's watched but remained impartial and staunchly isolationist from any European 'entanglements', the Americans eyes fixed firmly on Japan, concerned about the growing strength of the Japanese military, reports of brutal actions on Vietnam and China by Japanese troops and concerned about the security of the Phillipines as well as other US holdings.
The war when it came in the summer of 1916 was seen as inevitable by all involved, even welcomed by some, mainly those who did not know the horrors of modern warfare as many young men would soon discover.
The Triple Alliance will lose.
Larger German army and smaller German navy coupled with more fortifications along the French-German border translates into more German troops in the East.
And while the Russian army in this TL 1916 will be better equipped than in OTL 1914, they probably missed some of the military reforms introduced in OTL after the lost Russian-Japanese war.
Add in open sea lanes for German trade during the war (no hunger winters) and I think they can hold the line.
Of course Conrad von Hötzendorf as the Chief of the Austrian-Hungarian general staff as in OTL might be able to "complicate" things.
France and Italy though will have a problem.
Coal.
In our TL in 1913 Italy imported roughly 11 million tons of coal. 10 million from the British isles. 1 million from the German Ruhr region via Amsterdam. All transported by ship. And Italy is totally dependent on those imports.
France produced only around 36 million tons of coal in 1905. Now subtract 11 million to support their ally Italy during a war.
Even if neutral Belgium sells them most of their yearly production of 22 million tons, France quite likely won´t have enough coal for iron and steel production in a longer war. They would need imports from the USA. I can´t quite see the Royal Navy agreeing to this?
Neither for France or for Italy?
As a comparison the United Kingdom (236) and Germany (121) together mined around 357 million tons of coal in 1905. Coal back then was an indicator for industrial might. Coal coupled with access to iron translated into steel. And steel was an indicator for military might. As in railways, ships, guns and rifles.
The Triple Alliance is totally outclassed here.
There are also the naval problems for the Triple Alliance.
The smaller German navy probably is still enough to contain the Russian Baltic fleet. Which would leave the Royal Navy free to deal with the French and Italian navies. And with the Italian navy still needing to keep one eye on the Austrian-Hungarian navy.
The French need to keep the sea lane open to their North African colonies. Colonial soldiers and supplies. So they either station a large part of their navy in Toulon / Mediterranean or risk losing that connection. The problems is that this solution also allows the Royal Navy to concentrate a large fleet in the Mediterranean?
I don´t envy France and Italy. Unless the Triple Alliance wins very, very fast (surprise attack of France through neutral Belgium?) they will lose in the end.