Iran is the key to Western and Saudi overtures toward Syria. It is believed that Syria is the “weakest link” in the Iran-led regional axis. The Saudis are extremely worried at the onward march of Iranian power in the region, and the prospect that this may be taking place soon under a nuclear umbrella. The West, and Saudi Arabia, evidently hope to initiate a process of coaxing Damascus away from Teheran. Saudi power is financial power. Riyadh could offer the economically ailing regime in Damascus a host of economic incentives in return for distancing itself from Iran.
And finally and most fundamentally, the Syrian alliance with Iran will not be sacrificed in order to re-build relations with Saudi Arabia, or with the West. In case anyone had failed to notice, the Iranians are currently running rings around the US in the “negotiations” over the Iranian nuclear program. It may be assumed that the Ba’athis in Damascus have not failed to notice this. Good luck with the tax agreement.