By exaggerating threats, defining all responses to those threats in military terms, dismissing dissenters as weak and deluded (even when they prove right), and being incapable of questioning their principles, they repeat the same mistakes again and again.....
Iran has gained an awful lot since 2000. In Iraq it has gained a partner with the Shiites easily dominating, now that the Sunni dictatorship has ended. Iraq alone gives Iran a huge amount of strategic depth into the Middle East that it didn't have between 1979-2002.
Hezbollah has risen to full political and military power in Lebanon. Bahrain may present Iran to get its toe in the door of the Arabian peninsula. Finally Egypt is more likely to be more independent than previously.
But on the Syria question itself there is a lot of grays. Could be that Syria if Assad goes will still be friendly towards Iran. After all Syria is going to remain as Anti Israel as ever because that is the will of the Syrian people who want the Golan back.... Also Syrian military must know that continuing to supply weapons to Hezbollah will allow them some continuing power in Lebanon....
Finally with Turkey I don't see it moving all that far away from Iran. In fact trade has been increasing and there is the Tabriz Ankara pipeline, Nabucco and all the wriggling about Iran on that one and the proposed Persian Pipeline which will pipe gas from the Fars gas-field in Iran over Turkey and into Europe ending in Switzerland.
Turkey ain't gonna move away from Iran. Syria's foreign policy with regards to Israel seems popular with the people and unlikely to change. Egypt will likely be more independent. Iran has gained a lot of control within Iraq....
The idea of Iran suffering "diplomatic isolation" is not even a threat....