However, this could be the outcome where Assad stays in power in a much smaller Syria in the south. It is logical because of what has happened in the past in previous proxy war conflicts around the world especially during and just after the Cold War.
I don't really think it is realistic to push Assad out of Syria entirely because Iran and Russia aren't going to let that happen militarily. However, Iran and Russia might allow a partitioning of Syria as a marginally acceptable outcome as long as Assad stays in power in the Southern part of this partitioned area.
Though this isn't a perfect solution it might help the millions of displaced people around the world who lived in the Northern partitioned Area of Syria to return home to their previous lives (if they are Sunni Muslims). Like I said it isn't perfect but likely this might happen given all the variables on the ground there now.
IF you want to read more about what happened during the 1990s in Bosnia, Serbia and Yugoslavia here are some facts from Wikipedia:
Serbia in the Yugoslav Wars - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Serbia_in_the_Yugoslav_WarsSerbia was involved in the Yugoslav Wars in the period between 1991 and 1999 - the war in Slovenia, the war in Croatia, the war in Bosnia and the war in ...WikipediaBosnian War - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Bosnian_WarThe war was characterized by bitter fighting, indiscriminate shelling of cities and towns, ethnic cleansing and systematic mass rape, mostly led by Serb and, to a ...WikipediaKosovo War - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Kosovo_War230,000 Kosovo Serb, Romani and other non-Albanian civilians expelled. Albania .... 7.1 Serbian war crimes; 7.2 Albanian war crimes; 7.3 NATO war crimes.WikipediaYugoslav Wars - Wikipedia, the free encyclopedia
en.wikipedia.org/wiki/Yugoslav_WarsThe wars were complex: characterized by bitter ethnic conflicts among the peoples of the former Yugoslavia, mostly between Serbs and Montenegrins on one ...WikipediaThe History Place - Genocide in the 20th Century: Bosnia ...
www.historyplace.com/worldhistory/genocide/bosnia.htmDuring World War II, Yugoslavia was invaded by Nazi Germany and was ... A new leader arose by the late 1980s, a Serbian named Slobodan Milosevic, ...