The consequences of neutral Ottomans are fascinating. Firstly, we can pretty much rule out a CP victory. The war will likely end sooner, but how much depends on a lot of things, including chance and, more importantly, whether the Ottomans let Entente shipping through the straits.
If the Russians are able to receive modern war materiel from the west, they may not suffer such a meltdown in 1915, although they're probably not keeping Warsaw whatever happens. Meanwhile, all those forces that would have been bound for Gallipoli will presumably be comined with all or part of the Salonika force, only without Bulgaria entering the war (which they probably wont), Serbia can probably hold on long enough for it to become the Serbia force.
And then in 1916, with a better-supplied, better-moraled Russian army launching the *Brusilov Offensive from a better start line, plus an ongoing Serbian front, the Italians taking Gorizia, and probably a Romanian attack on Transylvania, we're looking at a Hapsburg breakdown a couple of years early.
What this doesn't mean is a decisive defeat for Germany, interestingly. Obviously when A-H breaks, Germany's position is hopeless, but with Germany occupying Belgium, Poland, and parts of France and America not involved, Germany is sure as hell not getting a Versailles treaty.