"The lines of Tribe shall dissolve"
This is the fundamental problem with Obama and the Democrats - they believe that Central Government trumps State, Local, and Tribal governments... there is no lower level sovereignty - only cogs in the machine that make the federal government work.
Let me tell you why it is important that the line of tribe NOT dissolve.
* We are a nation of free individuals who CHOOSE to support a common goal - freedom, peace and prosperity.
* We are a nation who has a government - NOT a government who has a nation.
* We are a collective of individuals representing local differences - regional defining factors - specific needs and wants as a resident of our region and community - not a collective of drones.
The "melting pot" signifies the importance of commonalities as a nation, but it does not indicate the need to dissolve ties to regional needs, regional norms, regional values. To expect rural Kansas to accept the norms of San Francisco is absurd - though we should be able to come together in peace and debate our differences... THAT is the real intent of the government.

I would assume that Obama picked his words very carefully - so why would he specifically mention "tribes" if not for a warning to the Indian Nations that their differences will not be resolved under his administration - and almost as a threat that their nations will be dissolved, and the reservations - the last of the lands promised to their sovereign governments - will vanish like the rest of the once great nations that inhabited these lands.
Let us hope that his words are not "just words" - and that this is not an affront to the Indian Tribes of this land.