Bashar won't be hung, He doesn't want the humiliation that faced Saddam Hussein. When the end is near he will kill himself, probably with a bullet to the head, maybe through the heart.
I agree that an internal assassination of Assad is very likely, especially as the most powerful of the rebel groups is made up of Syrian army defectors. The General's will form a united front to retain control, and hopefully end the civil war.
There are some X factors here. Assad is now protected by the Revolutionary Guard of Iran. They will protect him as long as the Ayatollah sees fit. Remember, they belong to the same Shiite branch of Islam even though Assad's (Alawite) is an offshoot. The Hezbollah of Lebanon is also there fighting for him. The Alawite areas of Damascus form a protective ring around the Presidential Palace. Of course, if that ring is breached by the Sunni insurgents and they storm the Palace, well the chess game is over and the king is captured, or in his case they would surely execute him on the spot; probably his family too. Something akin to the Romanovs. Don't forget the Russians are supplying Assad with some very effective weapons as well. Time will tell