That and just the simple fact that it's impossible to remain a little oasis of Turkish in a sea of Farsi and Arabic with there being many native elites still in a position of power. And I think they will largely adopt go with the former since at the time while Arabic was also prestigious it didn't have the kind of population of speakers that Farsi would in their empire.
Oh, reallly?
There are actually quite a few Turks in Mesopotamia. The only quesiton is, will there be more of them?
World Directory of Minorities
Middle East MRG Directory –> Iraq –> Turkomans
Turkomans
Updated April 2008
Profile
The Iraqi Turkomans claim to be the third largest ethnic group in Iraq, residing almost exclusively in the north, in an arc of towns and villages stretching from Tel Afar, west of Mosul, through Mosul, Erbil, Altun Kopru, Kirkuk, Tuz Khurmatu, Kifri and Khaniqin. Before the war that began in March 2003, there were anything between 600,000 and 2 million Turkomans, the former figure being the conservative estimate of outside observers and the latter a Turkoman claim. They are probably descended from Turkic garrisons or, in the Shi'a case, fugitives from early Ottoman control, although they claim to be descendents of the earlier Seljuq Turks. Approximately 60 per cent are Sunni, while the balance are Ithna'ashari or other Shi'a. Shi'as tend to live at the southern end of Turkoman settlement, and also tend to be more rural. Tiny extreme Shi'a communities (for example, Sarliyya and Ibrahimiya) exist in Tuz Khurmatu, Ta'uq, Qara Tapa, Taza Khurmatu, Bashir and Tisin, and Tel Afar. The Turkomans, speak a Turkish dialect, and have preserved their language (despite a strong linguistic Arabization policy by Saddam Hussein) but are no longer tribally organized.