I was reading an article last night about the current overall status of the Syrian Civil War, since it largely involves ISIS as well, and it detailed out the overall status of ISIS as well since they're fighting wars on multiple fronts. I wish I had the link, so I'll just go over it roughly:
Iraq: Since the introduction of American and coalition air power, ISIS has taken a beating, especially in Iraq. They're still far from beaten, but you're not seeing them making the same advances as they did 6 months ago. What ISIS is doing now is digging in. Everything rests on whether Iraq has the stomach to retake ground. If they can't retake ground, then there's no reason for the coalition to conduct air strikes, and ISIS knows this. The upcoming Battle of Mosul will be the true turning point of the war.
Syria: ISIS has made some gains in Syria south of Damascus since the focus of our air strikes are in Iraq, but they're also facing a more resolute Syrian Army as well. The Syrian Army is about half the size as it once was at the start of the conflict, but it's much more effective than it was before, as is making gains against the rebels in the north (Aleppo/Homs region). All things considered, the FSA (rebel groups) is largely fragmented, ineffective, and/or defeated. The Syrian regime's true enemies now are terrorist groups, with ISIS being the strongest, followed by al-Nusra (which is al-Qaeda). The important thing to note here is that every time we arm and support the FSA, the weapons fall into the hands of the Al-Qaeda.
(My words here) I'm of a different opinion on this one, but I think what we should be doing is arming and supporting the Syrian regime here. I get that Turkey, Saudi Arabia, and other countries want Assad out of the equation, and that they're also supported by both our and Israel's enemies (Hezbollah and Iran), but they're one of the two major powers in the region actively fighting terrorist groups on the ground. If they fall, you're going to see genocide on a whole new level. Unfortunately in this case also, the rebel groups are far too fragmented to be effective at leading a state. The only alternatives we have in the region are ISIS, al-Nusra (which is Al-Qaeda), or Assad. Who do you want in power? My vote goes to Assad. /end my personal words
Kurdistan: ISIS is learning that Kurds are not Arabs, and fight to a different tune. Kurds have long survived against overwhelming odds, but they lack the heavy equipment that they need to make truly effective gains against ISIS. The only reason the Kurds were able to oust ISIS from Kobani and make gains around Mosul is because of coalition airstrikes. Without air support, they'd melt under the advances of ISIS. Unfortunately arming the Kurds is a political issue. The Turks hate them, and the Iraqis don't want them declaring their own independent state. This sucks, because they're the only true friends we have in the region.
Jordan: New front. Wasn't mentioned in the article, but I'll add to this anyways. This will most likely be an extensive air campaign conducted by the Jordanian government in the southern Syrian region (where the Syrians need help most), but they could be a serious tipping point if they decide to utilize ground forces.