Based on your screenshots, changing the name isn't enough. You should also remove the Rank, coins, Activity, Merit, Avatar, personal text and Trust score.
Even than you would be able to identify many members based on their post history or member ID number, if that is also not changed.
How about a board where no usernames are shown at all? To prevent spam, let's add some Rank restrictions, and only allow completely anonymous posts there. You'll need to have a hidden post history for this. But as much as this be a really cool feature, it's probably easier to just create an alt account if you want to post anonymously.
That is a good idea, maybe we can name this board Bitcoin4chanTalk

I would like to hear what theymos and other OG members has to say about this, but I am interested to try this.