The Byzantine army wins the Battle of Manzikert. The Seljuk Turks proceed to Egypt instead.
The Seljuk, and consequently the Ottoman Turks, fail to conquer Asia Minor. These territories remain under the Crown. The Sultanate of Rum has not existed, and the population of Asia Minor is not devastated. Instead, it remains Greek speaking and Christian Orthodox.
The Seljuk Turks, having already been thwarted several times by the Imperial Army (siege of Caesaria, battle of Iconium), decided that Asia Minor was not within their grasp. After the battle of Manzikert, a milestone in the history of both the Empire and the rest of Europe, they came to terms with the Emperor and they never again harassed the eastern frontier of the Empire.