IIRC he was invalidated out of Austrian military service due to health issues (and the very high fitness standards of the pre-war Habsburg army). He might get drafted in late 1914-early 1915, but he may not get his draft papers until later in 1915 or even 1916, which means he'd avoid the big slaughters in the Carpathians over the first winter of war. After that given his fitness standards he might not end up with the infantry and end up a REMF, as he basically did with the Bavarian army. He might well end up on the Italian front. He could end up captured just as easily as dead or wounded, or even desert as many soldiers did in Habsburg service. Likely he'd end up hating the Habsburgs and their empire even more than he already did IOTL.
One thing is sure, regardless of whatever his fate would be, he'd never take over in Germany and likely wouldn't have amounted to much in Austria post-war.
Assuming OTL's economic isolation and punishment of Germany occurs, we should assume the rise of some militant leader to rise up to lead the Germans against their perceived oppressors. So, we'd better hope it's someone who makes some disastrous military decisions leading to Germany's second defeat.
None of the guys on offer in 1932-33 would have gotten the leeway Hitler did, because they were all Prussian ex-officers and were hated and not trusted by their neighbors. Hitler for all of his antics leading up to his power grab was actually given a ton of leeway by the Brits, Poles, and even French to a degree because he was an Austrian, not a German, and knew how to play the political game far better than the Prussians around Hindenburg did. Likely without an organized Far Right, which probably doesn't happen without Hitler to really rally all the competing personalities and inspire their loyalty, then Röhm and the Strassers, assuming they get to power anyway, would get coopted by Schleicher or someone else. So the traditional elite stay in power and are constrained due to the hyper vigilance that they'd inspire against them and German rearmament, because they were so threatening. Poland probably would topple a Schleicher government if he rose to power. So without Hitler around Germany never gets to revanche; plus the Germans military wouldn't get lobotomized by Hindenburg, who eliminated officers that were anti-Nazi and appointed the pro-Nazi von Blomberg, who further Nazified the military; the strategic minded officer in the end were fired by Hitler IOTL when they opposed his plans for continental war, so its very likely that with them still around without Hitler in the picture that the German military wouldn't be willing to embark on war due to the risks.