The comparison with the n-word doesn't apply here at all. Like I said before, no black high school will name their team the nikkas. And keep in mind that the Native Americans have more pride and respect for their history and culture than black people. So if redskin was truly a racial slur, they wouldn't attach the name to the high schools in their community.
And there are many tribes out there who don't have a problem with the name. I don't know why people find that so hard to believe and instead try to speak for them and tell them what should offend them. There have been polls done in the past with many of the tribes not being offended by the name. And Roger Goodell himself reaffirmed that. And keep in mind that earlier he was leaning towards a name change but probably changed his mind after getting more info.
http://nfl.si.com/2014/01/31/roger-goodell-washington-redskins-name/