Cui bono?
It would not be surprising at all. Any attempt to dismiss the possibility is just Russian/Syrian/Iranian propaganda.
I’d say there are multiple players and culprits, overall. The Iranian regime and Russians maybe the obvious ones.
“The World Needs to Know What Really Happened Last November (Paris Attack)”
Only a few will or already know what really happened.
But, other facts known to the public are that the jihadis shooting people at the concert hall spoke perfect French without a foreign accent (based on eye witnesses who survived the attack), were very calm and took their time reloading their rifles, until the police arrived some 20 or 30 minutes later.
Who knows and time will tell. But these coordinated type attacks more often than not have ‘inside help’.