The Shiite-Sunni split is, as always, just a canard, or to put it another way, pure bull****.
Any pipeline from Iran will be going through Turkey (another one already does).
The Gulf States wouldn't have trusted Syria with a burned-out match. Any pipeline they may build could (at this point) go through Israel (with or without going through Jordan) or Egypt, then to Europe across the Med floor.
What the Syrian conflict is *really* about and has always been about is Iran having geographic continuity to the Mediterranean in order to attack Israel while keeping the Arabs fighting amongst themselves.
The Russians got involved because of Obama-Kerry nuke surrender document "agreement" that is now up for reconsideration.
Possibly the discovery of gas and oil in Israel over the last few years had something to do with it, because that threatens Russia’s market in Europe. The Russian economy is not in the greatest shape and they depend on the European market, plus arms sales to Iran.
In Ezekiel 38, it talks about the attackers coming to take a spoil.