Seems like things are evolving away from black bloc to just wearing nondescript street clothing. No logos, no bright colors, but not all black, either. My understanding is that you maintain most your anonymity, especially with your head and face covered. And then you're also not standing out as the only person in bloc in a huge crowd. If you need to bug out you're less noticeable in the crowd. The old rules about having a change of clothes still apply.