Well they had a lot to gain should the Central Powers win. A POD would have them realize just how much internal trouble their country is in.
As for effects well, this frees up an entire front basicly for Russian and British troops. The British may try and reinforce the Serbians or Italians instead.
Because of course the loss of the entire Balkans to Christian-separatists and the continuous trouble from Armenian terrorist groups wouldn't have clued them in by then.
The Ottomans had a good idea of their internal threats. The young turks may not have grasped the external ones so readily, but they knew what threats there were from inside the empire. Honestly, in relative terms there weren't very many.
As for doing this, it is all about the navy, but by the time the Goeben came up, things were already somewhat in motion. Those German ships were given shelter and brought into Ottoman service as a response to Britain commandeering two ship that were being built for the Porte's navy.
That pushed the Ottoman's jarringly toward the Central Powers.
Absent that, it is easy to imagine politics in Constantinople taking a wait-and-see course. That would mean denying shelter to the German ships (who'd run for Trieste, no doubt) and keeping the straits partially open. Closing or limiting the straits would be a dramatic way to hurt Russia -
The Enemy - without putting the empire in jeopardy.
Once the Ottomans decide on neutrality, they'll stay that way unless the Entente somehow collapses. More likely, in 1915 they come under heavy British pressure to open the straits completely so the Entente can support Russia, and use the opportunity to squeeze a mass of concessions out of the deal. Russia does phenomenally better with the added support.
Meanwhile, the Bulgarians are desperately keeping their heads down instead of jumping on Serbia's back. So Austria-Hungary has both a much stronger Russia (and the Russians were more than a match for the Hapsburgs' military) and a surviving Serbia to deal with. That means less success against Italy, and more German troops sent south to prop them up.
The war ends early. Heck, even the Romanov's might make it out of this one.