I think the situation fulfils all the moral requirements for an armed intervention in Syria, with there being a dictator who's killing his own people to stay in power. I do think there should be an intervention of sorts- if that should include traditional thin-blue line peacekeeping or Post-Cold War peacemaking is debatable.
However there is a serious question as to if the international community can intervene. There won't be authorisation from the UN due to a Chinese and Russian veto, and Western powers have been fighting wars of considerable intensity for the past 10 years, still have serious commitments to Afghanistan, whilst also dealing with a massive financial crisis. So i doubt the West actually has the capacity to intervene here without causing severe military over-stretch.
The thing is, Assad's probably calculated this and so he's going to continue killing Syrians to stay in power, which makes me feel sick in the stomach thinking about.