Your big problem will be the Sultan. Even with an early Entente victory that leaves the core of Germany and Austria-Hungary untouched and allows their monarchies to continue, France and Britain will insist on heavy territorial cessions from the Ottomans. I doubt the monarchy would survive that.
But Germany and Austria-Hungary can easily come through. Abolishing their monarchies really wasn't a war aim until very late, except in the screechy propagandist "Hang the Kaiser" mode. I could see a settlement as late as 1917 that leaves both emperors enthroned while costing Germany perpiheral territory (Memelland, Northern Slesvig, bits of Prussian Poland and Silesia, Alsace-Lorraine) and the Austrians a bit more core stuff.