First off, people rewrite history all the time. It's happened before and it will happen again. The best way to remove the shining legacy of Thomas Jefferson is to rewrite history to show him as a bigoted slave owner.
I don't think they'd rewrite history books though, because I don't think anyone has hid that he owned slaves....it was pretty much out there, so they couldn't really change the books on that. (However, Jefferson was apparently romantically involved with one of his slaves, and that she might have given birth to illegitimate kids).