The Turkish public is divided into two camps, pro-Erdoğan and anti-Erdoğan, and they're damn near 50%-50%. That was reflected in the referendum, which ended 51.4% to 48.6%. Since the referendum, Turkish economy has been dealing with serious issues, the value of the Turkish lira has plummeted. That has to do with Erdoğan interfering with the free market and the Central Bank policies. His supporters are adamant that the economic situation is due to "outside forces trying to push Erdoğan out the door by influencing the market". However, the less fanatical people who had been voting for Erdoğan for economic reasons may react differently.
The media is correct in saying that a prediction is impossible. This is the first time since I've been following politics closely that I don't have a clear idea about the outcome. The few respectable polls in the country point to an election that is very much on the fence. Gun to my head, I'd guess Erdoğan and his allies lose the majority in the Parliament and the presidential race goes to a run-off, but Erdoğan ends up winning the run-off. I would not be surprised with any outcome, though.
As for İnce, he's good, I'll be voting for him. He's from a Kemalist background but has softened his stance on a lot of issues and has embraced a more social democratic platform in his campaign. That has been the case for his party, CHP, as a whole under the leadership of Kemal Kılıçdaroğlu. Kılıçdaroğlu never quite got the crowds behind him though, because he's not much of a public speaker. That's İnce's strength. In terms of support in the run-off, it'll depend on the religious conservatives who don't support Erdoğan, really. The Kurds seem to be okay with the idea of supporting İnce in a run-off, as do a lot of the Turkish nationalists. An Islamic conservative party is allied with CHP for the parliamentary race, but whether they can convince their voters to vote for a secular social democrat over a religious conservative that they don't care for is questionable.