>Kind of like the Auspicious Affair (Vaka-yı Hayriye) of 1826 whereby the Janissary corps were abolished once

I abhor taking a contrarian position just for its own sake, but in this case, I simply must. I disagree that the Auspicious Affair was the death kneel of the Janissaries. The downfall of this corp class was self-inflicted: what started out as an effective military (and in some cases para-military) institution degenerated into a mafia of sorts where the Janissaries would "shake down" every new administration for an extra buck. Furthermore, the fact that the corp ventured into commerce and other non-military activities disengaged this warrior class from combat duties: these guys just sat around, scheming on how to get their way, and "wet their beaks" in every possible way imaginable (brothels, unsanctioned annexation of Serbia, et al). It is unimaginable that the Janissary corps could have been so 'easily' disbanded in 1826 if they had not lost their legitimacy, battle readiness, and integrity (integrity in this case is only in relation to my earlier point about their corruption). Their downfall was their own undoing.

>there were rumors

It is unimaginable that Turkish intelligence services knew nothing about this. While organizing a university students' strike is difficult, picture the logistical effort expended on a military coup, to say nothing of the heated arguments and active wooing that undoubtedly went on in various places in and outside Turkey itself. Military coups do not develop organic leadership; there needs to be a solid command and control structure deliberately and forcefully communicated to coup participants. Rules of engagement must be determined to avoid unnecessary confrontation and thresholds must also be established so that the leadership knows when goals have been accomplished and when the game is up. A case must be made to the rank and file and these soldiers allowed to make a conscious decision, the risk of dissenting soldiers informing the authorities notwithstanding. A battalion of men and the equipment and support necessary for them to function must be made available for independent and effective operations: weapons, armor, transportation, fuel, air support, flight control, encrypted communication gear, carriers/tanks, etc. This stuff takes more than a day or two to make ready and neither does it stroll out of barracks all on its own. Furthermore, elaborate plans must be made to severe connection: analogue, digital, and Internet broadcasts. Your guys need to have the complete attention of the entire country. Interventions must, therefore, be made at the ISP/broadcaster level. It is feasible that the political administration of this Erdoğan fellow allowed the situation to escalate as it so violently did.

>This coup attempt could not have come at a better time.

Perhaps this is why the political administration needed this to go through (somewhat). However, we must all be cognizant of the fact that there is a parallel society that operates within Turkey (forgetting for a moment that there is a strong secular movement, particularly in the west) led largely by Gülen. This section of society will not melt away.
I think that the coup came at the worst of times for the incumbent. The fact that it was unsuccessful means that Erdoğan, in appeasing his supporters and demonstrating resolve, must 'act tough.' However, as in almost all other coup cases in the country and thanks to Turkey's long and storied history with its military, compromises will have to be made. There will be a purge (I speculate), but not one that catastrophically degrades the ability of this new Janissary corps to stage an outright or 'palace' coup in the future. Secondly, the secular movement will be emboldened by the revelation that a section of the Armed Forces (perhaps the movement's strongest and most consistent ally) is fed up with the Islamization of the society at the expense of the society. The Gülen camp, on the other hand, will be emboldened by the fact that Erdoğan is not the tsar that he makes himself out to be (not that they did not know that, but now they have real, demonstrable, and irrefutable proof: Look, coup! Weak!) and will propose that the camp's exiled leader is the panacea to the unification struggle that is sure to follow. Domestic politics is not cast in stone and whatever the incumbent does over the course of the next months will not discount the divisive tragedy of modern-day Turkey. Turkey has just begun (again) the search for its soul. This time, however, there is little chance that the king will have his way at the expense of all other interests- there will be no decisive victory or vindication. This country is just too big to contain anymore.
From yours truly,
Arm-chair general