They must not be asking that question around here... The dumbest thing is how short sighted Russia, China, etc. are about this. Do they think a post-Mullah Iran won't want to sell oil? Get rid of the political instability and I bet their infrastructure will improve, their production will increase and their oil price will tend to fall (at least in so far as supply factors have an effect, growing demand may continue to push up the price point, just not as far up as under the status quo.) Realistically all the Mullahs can threaten with oil is temporary shortages.
Maybe they look at how Iraq has gone and think, hey!, "post-Mullah Iran will be unstable, won't respect our current Sino-Persian contracts, production will fall, and oil prices will increase even further."
Maybe they think Iran would end up with a bunch of Shiite Muqtada al-Sadr's running around in chaos. Perhaps even Afghanistan doesn't reassure them too much.
Appeasement may be weak and wrong, but it may be logical for short term goals of 10-20 years.
China and Russia are NOT concerned about a Persian nuke threat because the USA is going to play the cop FOR THEM as needed when the time comes.
Walk in their cheap-chinese slippers for a mile and maybe you'll understand why they ain't hopping on the 'coalition of the willing' bandwagon. It ain't ICBM rocket science.