Interesting article, however somewhat limited in scope (perhaps the book you've wrote it for explores it further?) to the situation in Americas. Here in Siberia, where Altaic & Mongolian and other peoples lived side by side the destinction is a bit different. As far as plastic shamen are concerned, one needs to understand that shamanic calling is a lifetime commitment, and a heavy one at that, as well as there are no magic bullets that will solve all the problems in one fell swoop.
But the shamans do help people to reconnect with their ancestral roots no matter if they were of the same tribe or not. The only thing is that the rituals that work for one people aren't going to be effective for the other, because they did things differently.

As far as shamanism being perceived as a threat by the princes, we have the example of Mongolia, where it was brutaly supressed and supplanted by Buddhism, to keep the warlike tribes at bay. Shamanism has a heavy emphasis on personal power and responsibility towards ones actions and the community. Another thing, that we can learn from shamanism is that the dichotomy between individualism and collectivism is deceptive, because neither is more important, and it is both important for the individual to look after themselves and the community they are part of, but they can only do it if they are concious of their own acts and responsibility. I plan to write about Buryat Mongolian shamanist tradition (called Böö mörgöl) with #shamanism tag, hope to see you in the comments. :-)