You are probably right that this won't lead to a larger regional conflict. However, just how desperate are the Saudi's for distraction? What steps will they take to prevent a collapse? Their crazy cheap oil has been a pain for US oil and natural gas development. The US media is increasingly unfriendly. But, Israel is not pleased with the US getting cozy with Iran... I do not think that Israel will sit by while the US swaps the Saudi Arabian alliance for an Iranian one without playing some cards of their own. I'm not saying that Iran and Saudi Arabia will divide Iraq and collide, but what if the Saudi's Sunni coalition against militancy decides to start 'fighting ISIS' in Iraq with boots on the ground? Will the Iraqi Sunnis be upset by that development? Will the Kurds? Will the Israelis?
I think the House of Saud lives in petrifying fear of a Muqtada al Sadr. Of an ibn Taymiyyah. Of an Abd al-Wahab. The House of Saud has been buying baubles for the rich and sops for the poor but one charismatic fundamentalist interested in burning out the impurities and the fat Benz drivers running things now are going to do a poor impression of TE Lawrence's nobles. I think, in many ways, they dwell in a cage of their own creation, which is one reason they frolic abroad so much. I think Netanyahu made a grave misstep when he aligned himself with the GOP against Obama. Traditionally, Israelis practice skullduggery. Traditionally, democrats practice skullduggery. Traditionally, Republicans go boots on ground and get mired in grand adventures and every time the Israelis roll out the troops they lose face and influence. Boots-on-ground in the Middle East right now is a fuckin' mess while skullduggery runs the world. Iran views Israel as an unfortunate historical anomaly, but they also celebrate "Death to America Day" and they seem to be able to overlook that in the interests of capitalism. I think now that they no longer need an Ahmadinejad, they're going to return to pragmatism. Iran is repressive and hidebound but Iran remains staunchly Persian. Fully a third of Saudi Arabia is foreigners and most of them hate being there. Iran is in zero danger of an uprising at the moment while Saudi Arabia... ...well, my money's on the Persians.