However this may simply be the calm before the storm. Egypt's military government has been facing continued protests in Tahrir Square calling upon them to give up power. Even though the government has resigned and legislative elections are scheduled for Monday, this may still not be enough to the people, who may seek quicker change and a military with a less integral role in Egyptian politics. In that case, more violence is likely to erupt, or even a second revolution against the military government.
Syria is also becoming more dangerous, with Assad now an international pariah. Many middle-eastern nations have called for him to step down, including Turkey and Saudi Arabia, and the Arab League has levied economic sanctions against Syria for Asad continuing the crackdown against his own people. Here the future is much less certain. Perhaps Assad may actually cease the crackdown if the economic sanction damage Syria's economy (though this is unlikely because several nations, such as Iraq are ignoring the sanctions). There is also the possibility that the Syrian opposition may morph into a full-fledged rebellion, like in Libya. However, unlike with Gaddafi, who was a pariah even among other Arab nations, there is likely to be much less support for international intervention, particularly if it risks upsetting the regional power dynamic with Iran.
The one thing for certain is that this is not the end of the Arab Spring. The United States should be prepared to deal with further outbreaks of violence, and more shifting power dynamics in North Africa and the Arabian Penninsula.