Since Syria is a Shiite nations and Saudi Arabia is Sunni, I doubt the two would unite. Rather there is a Syrian-Iranian-Iraqi coalition in the making, which is much more of a danger to Israel. It is also a danger to the Saudies, which may explain why they are so interested in pushing any sort of peace agreement. The Saudis never fight their own battles. They may be thinking Israel will take care of the Shiites for them. It seems odd I know, but the Saudis seem to fear Iran more than they hate Israel.
Migrants rush train tracks as Budapest station reopens (dpa)
from the article: Gates says Washington to sell smart bombs to Saudi Arabia