One PoD: Franz Ferdinand's driver doesn't make a wrong turn.
The powder keg is still there, but it lacks OTL's spark.
More time allows even more industrial development in Russia. Maybe with a rebuilt Black Sea fleet the Russians attempt to push the Ottomans again and the Russo-Turkish war of 1915 (or 1917 whenever the next Russian dreadnought is finished) erupts into a world war when the French announce support for Russia and mobilizes, followed by Germany condemning French mobilization, followed by Austrian Mobilization. Britain will likely stay out unless the French get thoroughly thrashed and the Italians might actually stay out for their own good.
Well unless Russia focuses more on improving the peasants they are still going to need a quick win before it falls apart.Hmm, the allies gain a more powerful Russia, but lose Britain. Can they still win?
Where do we go from there?
A later WWI may even remove the Schlieffen Plan altogether as German military commanders come up with a new contingency plan to deal with a faster Russia. How soon that would happen or what kind of plan it might be I don't know.
In terms of British politics if WWI breaks out after 1915, there would have been a general election sometime in 1915, which based on the results of by-elections up to July 1914, would be won by the Conservatives and Andrew Bonar Law would become Prime Minister.
So would Bonar Law form a coalition government with the Liberals and Labour sometime during the war, as Asquith did with the Conservatives and Labour in 1915 in OTL? There would be plenty of interesting butterflies in British politics: If there is no Asquith/Lloyd George split, that would have consequences for the Liberal Party. Also Austen Chamberlain might become Prime Minister in 1921, if Bonar Law had resigned because of ill-health.
The Government of Ireland Act 1914, which gave Ireland (excluding six north-eastern counties) Home Rule, would have been enacted in August 1914. So probably there would not have been the equivalent of the 1916 Easter Rising.