First, the USA and EU credibility were substantially damaged . They seems to be good at making promises, but when needed they aren't there. Compare Bashar Al-Assad, Russia and Iran's ally to Mubarak, USA's ally.
Second, no one will protect you but your own. International treaties are worthless in front of aggression since no one will enforce them for you. People are still being gassed in Syria according to some reports, and no one does a thing. Ukrainian soil was invaded by one of the sides who signed on an agreement to protect it in exchange of Ukraine's nuclear disarmament - the other signers USA and UK did nothing to prevent it.
Third, the international left is silent and worthless. It seems that ideals are relative and applied selectively. It means they are applied only when it's easy to do so. Liberals world wide did nothing to stop the conflict in Ukraine nor the massacre in Syria. I'm not even talking about human shields to fly over to Syria to protect its people - I'm merely talking about substantial demonstrations or funds mobilization. Ukrainians, Syrians and Russians are all left alone to their destiny.
Fourth, if you are not wiling to die, someone will kill you. Yes, you are right...it sounds like the jungle law. If Ukraine would have posed fierce opposition in Crimea, even is symbolic - showing its people determination to protect their territory, there is a chance that Putin would have reconsidered his moves. Given the anemic response of the west and the disgrace of the Ukrainian army, there is no chance whatsoever that the Russian army will stay away of East Ukraine and the Russian population over there. Why should they?
The domino building of global order is quickly crumbling and we will all pay the price.
Again, brutal force as the upper hand - the more brutal you are the less chance there is someone will stop you.
The healthy, wealthy and well fed idealists of EU and USA, again lost any survival instincts. They may be afraid or just living in a world of fairy tales.
The only 'good' side to this sad story, is that if we thought that the world was being racist when not helping out the millions massacred in Sudan, Burundi and other places - we can rest assure that they won't help also 'paler' kinds. Sad.
Now just come to think how will it affect other conflicts for an instance the Israeli-Palestinian conflict. Will anyone trust international guarantees, agreements and forces? Or will instead everyone uphold Darwin's simple and so-painful true of survival of the fittest?
I think you already know the answer. Just go to YouTube and search for 'Syria'. I promise you wont sleep tonight after watching this.