1.  Degradation of their unique culture if their isolation is destroyed.

    Then why do they want highspeed internet, and hydro power, not to mention the hundreds of other things that are not part of their unique culture?

2.  Decreases in their payments from government, which are lower for communities that are connected by road.

    So why aren't the reservation that are connected by road not demanding the connections be severed? Why are the natives on the Shole Lake Reservation so happy to get a road? see: http://www.cbc.ca/news/canada/manitoba/shoal-lake-40-first-nation-road-manitoba-1.3368558

possible that some band governments might fear an erosion of their power and control if the communities are opened up to the rest of the world.

  Now you may be onto something. However it is more likely that they know and fear that the "gravy train" of money for studies, and all expense paid trips to the big city for meetings will end if they settle things. Besides it is nice to be wanted by people with money, who would want that to end?