I agree that there is no avoiding a catastrophe.
I also agree with Jim that the international community has a duty to act to prevent such crimes against humanity as we have seen in Syria.

IMO, Assad is guilty of such crimes, and should not remain in power.
Annan has openly said the same.
Western and Arab League governments have for some time.
Russia and China want him kept in power for reasons of self interest

Concerted action by UN is vetoed.
Military intervention is not considered practical for several reasons, even if there was no veto.
Trade sanctions are ineffective because Iran, Russia and China continue to trade, including supplying more arms.
Economic sanctions by Arab League and West (seizing assets, not buying his oil) have halved the value of the currency and drained his foreign currency reserves. (Yes there is oil Jim.)

The transition of rule is bound to be messy.
The opposition are disparate with many ethnic divisions.
The Un would try to get an agreement for a temporary government of national unity with safeguards for minorities.

I share your sense of hopelessness McG, but our governments should not give up as you seem to be suggesting.

I note you do not criticise the countries arming and supporting Assad McG.