isis will continue fighting for further control. They flourished in the vacuum produced in iraq, what makes you think one in syria will slow them down? Also how long has nato been 'targeting' isis? That intervention hasn't even dented their influence
once assad is gone the west will just focus on iran. Did we stop at afghanistan? libya? Lebanon? Iraq? Nope, it's not that simple.
See how quickly we pledged boots on the ground in syria after russia actually started hitting isis? And do you think russia is gonna stand by and let the gulf build their gas lines to europe, and cut their russian dependance? Relying on russian natural gas is the main reason russia is still functioning, and they won't be willing to just roll over and accept this fate.