To add as well: Evan has said to me that the reason the war stopped as because the Turks were just done. They managed to play the time game in much the same way Ho Chi Mihn played the time game against America. A physical tactical victory was impossible for the Vietcong and they knew it. However they knew a country could grow war weary and wanted to prolong the conflict long enough that the people demanded an exist strategy.

Same thing that happened in the Second World War, almost. As that conflict was carrying on over two fronts the American people were starting to demand out and the US military was having a hard time raising funds to keep up fighting. The war from a day-to-day standpoint was funded through marketing War Bonds to the civilian population. But the War Bonds would only sell provided the American people had faith. And before Iwo Jima (I believe) the civilian moral was getting low. They needed a big victory to feel they had faith in the system so they may get back to funding the US war effort.

This is what happened in Turkey, except the Turks couldn't win the ultimate faith-restoring battle they needed in the mountains of Armenia. And let's examine the tactical implications of mountain combat: it's narrow. You don't get a lot of mobility in it. Early on Suleiman may have pulled it off because they weren't as stretched out as they were by the time Evan happened, but when Armenia decided they had enough the Empire was already stretched thin and distressed and the Sultan couldn't have been able to afford to send men in. And the scale at which they expanded at no doubt meant they were able to effectively rule that land.

To draw a comparison in antiquity: Justinian's Byzantine Empire. Over the entire reign of Emperor Justinian the Byzantines almost had turned the Mediterranean into a Roman Lake again. However the size of the Empire meant it was unruly and to keep up with its day-to-day means meant it needed high taxes. Same could be said to Suleiman's Ottoman Empire, just with the added benefit of modern-day nationalist and ethnic identity.