CHP won in the past because most people in living in remote kurdish villiages weren't participating the elections. Also as you've mentioned there were no political movement, before PKK emerged, that promotes a kurdish national identity in some sense. Such movements were crushed back in 20's and 30's.
Well economy is a factor that might cripple AKP votes. The growth rates are down, TRY is devaluating against dollar. However people also seek for alternative. I mean the day that AKP lost the majority in the parliament there should be a coalition among MHP, CHP and BDP (the kurdish part). Such a coalition will definitely not work, so people stand behind AKP.
That's why presidential system was actually a chance for CHP and I don't know why but they've rejected. Turkish people afraid of coalition (they had bad experience from 90's). However presidential system overcomes this phobia and the candidate of CHP might had a higher chance of success in an economic downturn.
Kurds are seeking for federation. They always publicly tell that. But this will hurt AKP's image among the right wing voters. From a geostrategical perspective I guess AKP is looking for something in return. There might be a federation but entire Kurdish region (Iraq + Syria) will be a part of Turkey. AKP promises federalism and international recognition, dignity, future EU membership maybe and also the most important thing is NATO shelter. If Kurds in Iraq and Syria joins Turkish kurds and forms a single federation under Turkey umbrella they will be untouchable in the Middle East.
AKP can easily sell this to it's own right wing voters because they'll say "we've made Turkey a bigger country, we've conquered". They will market neo-ottomanism to their voters. In such a scenario AKP will rule a very very long time.
Partition will not be on the table because Kurds are not ready for it. They are extremely underdeveloped in their regions and that would end up with destabilization. Besides they won't become a part of International Community so easily. They should wait at least 10 years to be able to enter WTO, it's a very big chance that they won't be able to make it in NATO, they should make regional politics and form their own strategies etc. which they think it's not the right time. I mean Syrian Kurdistan was a trial that showed them how hard it is.
Partitioning is the only option that can finish the AKP rule in the short term. Turkey puts a buffer state between itself and the Middle East. Turkey becomes a true nation-state and becomes ready for a real post-modern era. Unlike US, Turkey does not have the cultural attraction and economic resources to keep a group of people from different cultures all togather inside and grind them. If I should make an analogy from thermodynamics, it creates too much entropy for Turkey. Turkey can afford lower energy levels which is a true nation-state at first. If this happenes Turkish EU membership becomes easier because people living in the Western parts are culturally and ethnically close to Europe.
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