While it may make all the sense in the world to go with a PMC solution, the member states would never go for it...no matter how painful it would be to go without.

That's one of the greatest failings of the utopian-esque drama that is called the UN. Country prestige is one of the foremost things on the mind of contributing states. Second most important is likely keeping their soldiers happy with a little extra pay (which US forces see none of when part of these lash-ups).

Add to this the fact that Blackwater is a PMC that grew up within the belly of the great Satan, and the idea will go over like a fart in church. I'm talking about likely resistance from the Canadians and Norwegians too, who have their own peacekeeping academies.

Blackwater will not be able to break free of the mercenary perception, no matter how hard it tries, so it will probably remain relegated to support services and smaller-level security details.

Again, it doesn't matter that Blackwater can do it better. Half the answer has nothing to do with capability.