Don't let the "legal strategies" of demagogues scare you. Activist judges have done great harm to this country over the years, as you have noted, but they cannot just take over the jealously guarded purse strings of Congress and dole out trillions of dollars to a whole class of Americans on the basis of skin color.
Slave reparations will never happen. Keyes and his buddies are just demagoguing to a particular group, which is a very sleazy thing to do.
More likely, though, is that the courts will rule bit by bit against corporations rather than the government. That way the people will just think, "Oh well, it's not my problem."
Keyes will have no effect on the issue one way or the other. But even if he did, his idea is only to exempt them from taxes. You must factor in the point that a certain percentage of them pay little or no taxes now, so it would only be as they are productive that they would be reaping any kind of benefit, and that would only be temporary.