I don't know why this would be the case. Every young generation starts off thinking that they'll change the world, right all wrongs, etc., and they end up just like the one before them. For millennials, your parents may have grooved out at Woodstock and protested against the Vietnam war or whatever, but by the time they were raising you, they were just as much supporters of the two party political system and either Reagan's, Bush Sr.'s, Clinton's, Bush Jr's., or now Obama's wars as their parents were supporters of Nixon or McGovern or whoever. Generational change may be profoundly transformative for those within a given generation (i.e., people of a certain age may be shaped by their experiences as young adults during WII, the post-war Civil Rights struggle, the hippie movement, etc.), but, people being as they are, there is likely to be a serious backlash against whatever the previous generation stood for by whoever's coming up. Why would all this stuff concerning race relations and foundational inequality be immune to this? It does seem like the emerging Millennial generation is more in tune with issues of privilege, they're less interested in things like voting: "Older Americans showed an overall voting rate increase between 1964 and 2012 (66.3 percent to 69.7 percent), surpassing the rates of all other age groups. Voting rates decreased for 25- through 44-year-olds (69.0 percent in 1964 to 49.5 percent in 2012), and for 18- through 24-year-olds and 45-through 64-year-olds as well." (
source)
As is typical, the older someone is, the more likely they are to vote. I am among the "older" Millennials, I suppose (I'm in my early 30s), and I'll put it this way: While there are great many younger people doing good and important work when it comes to race and dealing with racial problems, most of it is coming outside of the channels by which people typically obtain and keep political power. The protests in Ferguson, for instance, may have captured the world's attention, but the people participating in them are still economically depressed and socially disadvantaged, so good luck waiting for any of them to become senators or whatever. That reality, combined with the fact that this newest generation is for the most part almost exclusively obsessed with personal 'gender identity' issues which do nothing in themselves to help the political, social, and economic standing of racial groups (read: if Caitlyn Jenner were a poor Native American, black person, or Latino, there would be no "I am Cait" show, and no ESPY award; "being your true self" does nothing for anyone outside of your immediate circle -- generic, monetizable 'awareness' be damned), pretty much guarantees that race-based inequality will be around for a long, long time.