The Qatari gas pipeline to Europe would provide direct competition to the Russian gas pipeline to Europe as well as Iranian gas sold to Europe via Russian pipelines.
I just don’t see any possible outcome given the current state of the region and any possible turn of events where the pipeline might be constructed.
If Assad falls the rebels will take over and chaos ensues, pipeline is improbable.
If Assad prevails the Russian’s have their way and the pipeline is not built.
As I said before, unless OPEC is willing to raise an army and get their hands dirty in this civil war there is little chance that they will start construction of the pipeline in our lifetime.
The only way the I think pipeline happens is some interested party (OPEC) finances the rebels just enough to permit them to overthrow of Assad then brings in overwhelming force to take control of the country while the rebels are weakened.
Of course Iran would not be pleased and would probably enter the fight. So there is a good chance that it could spark a regional war.