Brett,
As I understand it, each post would have whatever you entered in the Full Name field-- i.e. in your case it would contain Brett, no last name.
That is the thing that makes this whole thing manageable, as far as I'm concerned-- you can enter as much (or as little) information as you'd like/are comfortable with, and that is all that will ever show up.
Don't want your email exposed? Fine! Mark it as non-public, and it won't show up. Don't want anything more than your first name showing? Easy-- just put your first name only in the Full Name field.
Et cetera, et cetera-- As far as I know, you aren't required to publicly reveal anything about yourself to be a member here; the proposed change alters that not at all.
Brad