In reply to mark s:
Facebook and twitter could easily geo block those countries. The ISP's could drop the BGP peers and all of their internet traffic. The reason why they are allowed to continue is it provides intel on ISIS operations, and it's a handy source of real time targeting information.
Groups like Syrian Electronic Army, SEA, are clued up. They hacked the US army, very publicly. It wouldn't be surprising if they followed the anons, and took their own counter measures. If the Paris guys were using in game chat, to avoid monitoring, that shows a reasonable level of awareness.
Any attack on the Syrian internet infrastructure will probably hurt the poor sods caught up in the middle of it, who just want to know how to get out of the country, or to contact relatives etc. It will affect intel gathering. The only thing that will be reduced is the number of pictures of people posing with guns or severed heads. Their fan base will still be rooting for them and information or propaganda will leak out in other ways.