There are a number of obstacles preventing the PKK from laying down its arms. The first is that the PKK has not mentally prepared itself to even discuss laying down its arms. Whenever one mentions possibility of quitting violence and returning home, the PKK considers it as a complete surrender, which is totally against the main philosophy of the PKK. Therefore, I don't think there is a foundation or mental preparation to discuss such a possibility with the jailed PKK leader Abdullah Öcalan. Thus, what the Turkish press is doing is at best mere speculation.
Further, given the fact that the PKK is a transnational organization, disarmament could be a big problem for non-Turkish Kurds who fight for the PKK. The PKK would need to send its Syrian members to protect the newly emerging PKK state in northern Syria. And how would the organization deal with its Iranian members? Would they also accept what Öcalan accepts?
Worst, although Öcalan is an influential leader, he has directly orchestrated the PKK for some time. Instead, the PKK is run by an executive council for which Öcalan is only a symbolic figure. Therefore, it would not be easy for Öcalan to convince the committee to lay down their arms. In addition, the committee has its own priorities which I do not see as synonymous to Öcalan's. Therefore, the imprisoned leader's chances in convince the committee is even less likely.
Second, it is the worst time for the PKK to discuss possibility of laying down its arms. The PKK is an organization that benefits crucially from major crises. For instance, in 1991, the PKK enlarged its weapon capacity all the while people were expecting that the collapse of the ideological foundations of the group, Marxism, would also doom the Kurdish militant group. In opposition to general expectations, the PKK came back stronger after the 1990s. Similarly, the PKK even survived the arrest of Öcalan in 1999 and managed to resume its fight right after American invasion of Iraq, growing only larger and larger.
More importantly, as the AKP government tries to restart negotiations with the PKK, the PKK stands stronger than previous years. Moreover, it is also not a very good time for the PKK to negotiate its future when the future of Syria is uncertain. When there is so much uncertainty in Iraqi Kurdistan and in addition to the unpredictability of events in Iran in the coming years.
In the current political environment, it is less likely for the PKK to agree to a ceasefire. Forget about it laying down its arms.
The PKK would agree to disarm, but only on the condition that Turkey allows the group to reroute to northern Syria and recognize them as legitimate force to deal with. For many PKK members, even this agreement would be considered a defeat, but Öcalan and the PKK leaders are smart enough to see that such a gain for the PKK would bring new opportunities in the region for the long run.
If the PKK manages to persuade Turkey, which does not seem too hard these days, it will not only legitimize itself but also secure an oil-rich region in Syria, where it would not need to collect money to establish its own government.
With such a deal, the PKK would not technically be laying down its arms -- it still keeps its weapons but agrees to not use them against Turkey. To me, if there is any deal between Öcalan/PKK and MİT, the only feasible one I see is such a deal on Syria.