I'm looking at this from the non-Sunni Arab point of view. What you're saying might be a rational idea in the short term, but in the long term who in the ME wants to be satellitized by the Jews? It would be a huge betrayal of the Baathist ideal for the Shia and Alawite Arabs to ally (i.e. subordinate) themselves with the Jews, and it would alienate them from the Sunnis more than they already are. No Arabs should be allying themselves with Jews except in circumstances of utmost need.
Don't forget the fate of Israel's allies when the IDF deserted southern Lebanon in 2000. Sure, ME politics are cut-throat and every group betrays, but it's really, really historically rare for any group of people to ally with Jews and profit from it in the long run.
The defense industry cements those ties. The relationship is beneficial to all parties and so came together naturally. Unlike in the US where the parasite has to force the blood flow with media and lobbying.
Shia have openly begun speculating on Arab television that if the Shia-Sunni war does not fizzle out that Levantine Shia will be forced to make an alliance with Israel. In return for a non-aggression pact, a severing of ties with Iran, Hezbollah and Palestinian resistance, a blessing on Palestinian collaborators... then a pair of Arab Shia statelets running along the Levantine Coast could secure immense funds and arms from the US. This is only possible if Occidentophile Shia could oust Hezbollah and Assad's Baathists. The Shia rejection of Hezbollah and Assad could then spread to rejection of the Iranian backed Shia parties in Iraq in favor of Anglo-American backed Shia in the tradition of Ayad Allawi (perhaps led by him). This secularist, pro-Western youth based movement could then link up with the irreligious, anti-theocratic Iranian left, which has recently taken Tehran in elections and would be glad to reform Hezbollah for American goodies (sanctions lifting followed by lucrative contracts).
US-backed Arab Shia would be in the same tent as the juntas and monarchies in Egypt, Jordan, Saudi Arabia, the UAE, and Yemen and would be instrumental in beating back Sunni Islamist groups like Al Ikhwan and the Qaedasphere. Most important of all, by the Syrian Shia dumping Assad and shaking hands with the US, America will use its position in NATO and the Friends of Syria Group to force the FSA into a ceasefire with the Shia rump state (whatever borders it holds) and to turn its guns on Al Nusra... as it would like to do now but can't. Together, US-backed Shia and the FSA could form a coalition government, delivering Damascus into Washington's hegemon. Next to Burma, Yugoslavia, South Sudan, East Timor, and so forth... it'll be an excellent addition to the list of nations that have been stolen from the Moscow-Beijing Axis and set orbiting the Kabbalistic Askenazi Vassal Order.
Of course. The FSA is Syrian military defectors, mostly secular. With Assad gone, they'd need a Shia ally against Sunni Islamists and the Shia will need a Sunni force to protect them in their enclaves and neighborhoods from Salafis who'd like to confine them to the coast. With American money and contracts as incentive, they would have no reason not to.
The idea of two groups who've been killing each other by the thousands, forming a peace time government that crosses sectarian lines (even if they aren't salafists, sunni is their tribe) just because they are both enemies of salafists.... it's not realistic at all, in fact it's absurd. These last couple posts of yours have been very heavy on fantasy. "irreligious, anti-theocratic Iranian left, which has recently taken Tehran in election" are you talking about that clerically approved candidate who isn't even in office yet.... who is a cleric himself? A "reformed" Hezbollah receiving US weapons? A bunch of complex groups, enmities, and alliances, breaking and forming up at the drop of a dime, so they can fight those super cool underdog salafists? Ridiculous.