The outcome of Sunday's election in Turkey will likely be the same as the prior one in June. At least that is what the polls are saying:
The June results:
AKP 40,9%, CHP 25%, MHP 16,3%, HDP 13,1%, Voter turnout: 83,9%
The prognosis for Sunday:
AKP 41,7%, CHP 27,9%, MHP 14,2%, HDP 13,8%, Voter turnout 91%
The two main parties, Erdoigan's Islamist AKP and the hapless social-democratic CHP, will slightly win. The right-wing MHP will lose voters to Erdogan's AKP and the leftist/Kurdish HDP will also gain a bit. The many minor parties which do not make the 10% cut will be the overall losers.
The coalition perspectives will be the same as in June. There is no way the MHP would join any coalition in which the HDP takes part and after Erdogan reignited the war on the Kurds the HPD has no way to join with the AKP. But any possible coalition AKP + CHP or AKP + MHP will lead to a significant loss of Erdogan's powers. A lot of AKP's dirty laundry would be washed in public should CHP or MHP cabinet minister go through the files in the ministries they would take away from the AKP.
The AKP could still win a parliamentary majority should either the MHP or the HDP not make the 10% cut. There may be ways to arrange that like creating more "terror attacks" in Kurdish areas on election day or some other shenanigan. This report, interesting for its detailed view on the Turkish society, analyses that unlikely case.
But why should Erdogan agree to a coalition when he didn't agree to one in June? He could just let any negotiations fail, install another temporary government and require new elections in spring. Meanwhile he could further build his presidential empire and degrade the prime minister and cabinet to mere servants. He would have time to raid more media that are not toeing his line. Rumor says he is already planning for that. He would also have time to create some judicial case against the HDP that would would keep it out of a third election round.
The U.S. would hardly protest. Notice that there has been no outcry in U.S. media over the AKP takeover and yesterdays raid on the Koza-İpek Group and the various media channels it owns. Erdogan is openly threatening to bomb the U.S. Kurdish allies in Syria and no one is Washington is protesting this. There is also no outcry from the EU which is holding back a critical report on Turkey and Erdogan because he is threatening to unleash further "refugee" waves.
As Erdogan is getting away with each and every crime without even a bit of protests from his major NATO allies he is unlikely to hold back from further mischief. His constitutional role as president of Turkey is to be a neutral arbitrator not the partisan dictator he actually is. But no one in the international sphere is calling him out on it. I therefore expect that the election on Sunday will have results similar to the one expected above but that it will neither lead to a stable government nor to an end of Erdokhan's rule over Turkish politics.