Mark Levin was holding forth about this on his show this PM, and it sounds like this could be more symbolic than substantial. The Redskins do not lose the right to use the name "Redskins". The Redskins do not lose the ability to sue and win against some one using their name commercially without permission. What the Redskins would lose in such a lawsuit is the ability to prove their right to the name by showing it is a registered trademark; instead, they would have to show they have the right to the name through decades of use, which will be easy to do.
I am not a lawyer, so if I misunderstood Levin (or he got it wrong) I'll gladly listen to some who knows better.
Needless to say this move will be taken to court. Whether the Redskins will be able to get an injunction against this move so that their trademark remains recognized during litigation is an interesting and definite possibility.