I think that things can change, but people really don't. And your students are right about their diagnosis that they aren't going to have the same unfettered opportunities as White people, but the correct response is not to do nothing, but rather to do what you can to go as far as you can. Every accomplishment we make makes it more likely that generations later, maybe Black people can have comparable opportunities to Whites.
It might be more effective if, instead of refuting your students' belief that racism is permanent and will affect all aspects of their lives (because how likely are they to believe it when a White person tells them racism can go away?) and instead tell them that although racism is still here and will likely be here for a long time, it's worth it to deal with it and get as far as they can. In fact, it's a slap in the racists' faces to see them do well - and doing nothing just confirms what the racists have been saying all along.