With the success of Gallipoli, not the initial landings, but the push to seize Ottoman territories in Europe, including Istanbul, it is likely that the Ottomans MUST seek terms, even unfavorable ones. Greece has not made a decision yet and far too much eagerly sought Ottoman soil is now 'available'. If the Ottomans make a deal, they likely keep some that they lost in history, starting with northern Iraq and Syria(oil? they have oil where?). If not, Cyprus, Istanbul, and the coast around Izmir are over to Greece, which then enters the war. The Ottomans, cut off from aid and advisors, can be easily contained and eliminated at the leisure of the Allies.
With this, Bulgaria likely continues to give peace a chance(although the right allied bribe...), causing Romania and Greece to enter the war, dramatically strengthening the Balkan Front. Likely Macadonia and southern Serbia can be held, further diverting German attention from Russia.
As supplies pour in through to the Crimea, Russia is further strengthened by about 100,000 British troops(whose ideas near the Russians are just bound to get revolutionaries thinking...).
By 1916 Germany and it's one ally are in bad shape
Oh, and perhaps Great Britain can limit the number of ethnic groups and nations it promised Ottoman Palestine to below the low double digits?
Nah....