AMMAN, JORDAN — The overthrow of Syria’s Bashar al-Assad regime has opened the door to new dynamics in the Middle East, regional analysts say, with Turkey likely gaining superiority, Iran reeling and, with that, Iraq gaining more freedom from Iranian pressure. The Assad government in Syria spanned 54 years in power — first with the elder Hafez al-Assad and later with son Bashar of the minority Alawite community, a branch of Shiite Islam. Regional analysts say its fall marks a seismic shift in Middle East politics. Sinan Ulgen, a senior fellow with Carnegie Europe speaking during a Carnegie Middle East