That is not the US goal, he said, but it was looking increasingly likely.
CIA director John Brennan, speaking on the same panel, noted that the countries' borders remain in place, but the governments had lost control of them. A self-declared Isis caliphate straddles the border between the two countries.
Iraqis and Syrians now more often identified themselves by tribe or religious sect, rather than by their nationality, he said.
"I think the Middle East is going to be seeing change over the coming decade or two that is going to make it look unlike it did," Brennan said.
Iraq and Syria were artificial creations of British and French diplomats when the Ottoman Empire disintegrated on the eve of World War I. Each contains communities of Sunnis, Shia and Kurds. Iraq is run by a Shia-dominated Government with ties to Iran, while the Bashar al-Assad government in Syria is dominated by Alawites, also a Shia sect.
They are both fighting Isis, a fundamentalist Sunni group.
The Obama Administration's policy is that Iraq and Syria remain internationally recognised nation states.
Administration officials have, for example, resisted calls to send arms directly to the Kurds, who have a measure of autonomy in northern Iraq and have been America's most loyal ally in the region.
The Administration has insisted that arms for the Kurds be routed through the Government in Baghdad.
In 2006, then-Senator Joe Biden argued for splitting Iraq into three autonomous ethnic zones with a limited role for a central government. The George W. Bush Administration sought to keep Iraq unified, but Sunnis eventually became disaffected with a Shia Government in Baghdad that excluded them.
Kurds have been in continual disputes over budgets and oil with Baghdad, and have seized control of the northern city of Kirkuk.
In Syria, the Assad Government is hanging on with increasing support from Russia, leaving the country divided among government, rebel-held and Islamic State territory.
Saudis offer 200 mosques to refugees
Saudi Arabia has reportedly offered to build 200 mosques in Germany.
The Frankfurter Allgemeine Zeitung newspaper quoted a report in the Lebanese newspaper Al Diyar saying Saudi Arabia would build one mosque for every 100 of the refugees who entered Germany in extraordinary numbers last weekend.
The offer was seen as Saudi Arabia's response to the flow of people fleeing the Middle East for western Europe and calls for Gulf states to do more to help.
About four million Syrians have fled their country since the start of the conflict in 2011. The al Hayat newspaper reported that 500,000 Syrians had found homes in Saudi Arabia since the civil war began " but as workers, not refugees.
- AP, Agencies