The apparent statement is from around the 11th september 1914. I don't understand what he meant with it. Would he have been executed for causing the war?
The book is quite interesting but I think Strachan jumps from place to place too much and sometimes he doesn't provide sources making it a bit confusing to read.
Edit: Well I misunderstood it. I thought he meant that Franz Ferdinand would have been killed if he were not dead.
There are two layers to Conrad von Hötzendorf's gallows humor here. Firstly, the Galician offensive of 1914 was a disaster for the Austro-Hungarian Army and exposed the many deficiencies of the Dual Monarchy's high command. The execution of the war plans managed to make the worst of Austria-Hungary's already precarious position and Austro-Hungarian armies faced defeats on all fronts. Emperor Franz Josef I had launched an inquiry that cleared the high command of its deadwood. Four of the six Austro-Hungarian army commanders active at the start of the war were cashiered by the end of the year and the failures gave an added impetus to investigations of charges that the flag rank was a comfortable sinecure for aged generals. Conrad, as the chief of the general staff, bore a good deal of responsibility for this situation, but his importance to the Army's chain of command gave him a degree of job security.
The second layer to this comment is that while Conrad had a functional relationship with the Emperor, he had fallen out with the Archduke some time before the latter's assassination. After Conrad's reappointment during the Balkan Wars, ironically at the Archduke's own request, the two men frequently butted heads during maneuvers and in the imperial court. In light of this increasingly soured relationship, Conrad thought that Franz Ferdinand would have used the disasters of 1914 as further proof that Conrad should be dismissed; something he had argued forcefully in the two years before 1914. Franz Ferdinand had termed Conrad a "Wallenstein" in the 1913 maneuvers, insinuating he was a mercenary without true loyalty to the Habsburgs. As the quote indicates, Conrad thought that rather than being cashiered to spend the war in Viennese retirement, his imperial enemy would have used these failures to retire the Field Marshal permanently.
Of course there is a strong layer of self-pity and a lack of self-reflection in Conrad's attitude in this period. Although it would have been difficult for an accomplished commander to do better given the stakes against Austria-Hungary, Conrad had a marked tendency to shift the blame for faults on others and despite the privations of his troops, lived in a relatively comfortable headquarters and still kept some of the sumptuous habits of a prewar Austro-Hungarian flag officer. For example, he entertained his mistress for four days in January 1915 as his troops were freezing in Galicia and his day planner does indicate he maintained his prewar habits of reading the newspapers and taking time in the coffeehouses.
So some sort of disciplinary action might have been warranted against Conrad, but he had the fortune of fighting a war whose cause was the assassination of what was emerging as one of his main rivals within the Dual Monarchy.