I see this as a unique opportunity for these three nations plus others to work together.
Let the Russians land troops(27 vessels) in Syria and take in ISI inside those boundaries.
A Joint US-FR task force I can drive them out of Iraq and the two land forces can meet at the Syrian border. As I've said here before, two Brigade Combat teams is all it will take, one Heavy Mech, one Light. US 4th ID(MECH) and 10ID(MTN) supported by a Ranger BN and a Seal team. 30 day OP
I see no one on the UN Security Council that would oppose this.
That might be true, but the question is ... what then?
We know all too well how a prolonged presence of Western occupying force can lead to nothing.
I think the other route has to be taken. Support SAA, their allies and other regonal players from the air, support them logistically and intel-wise, and let them do the job of crushing ISIS. It will take more time, probably more casualties, but its doable.
One should just consider how SAA recovered from the string of losses, and started gaining ground in Aleppo province, and all that because of 40 or so Russians air-crafts, bombarding the opponents, plus some "advising" and of course rearmament in matter of weeks.
Press hard on some Gulf states against supplying extremists with weapons and money, and for Christ sake, prevent the shipment of ISIS oil via harbors of NATO countries such as Turkey.
And in the same, make provisions for a political deal, or at least cease fire between the cooperative anti-ISIS factions.
This is the core of the Russias proposal, and it seams its the most reasonable proposal yet.