DC didn't replace Wonder Woman when she was considered the weak link of the Trinity - and many people still see her that way, even now. They're not going to permanently replace a character with a far greater track record than Wonder Woman. Diana had a spinoff that got recently cancelled and it's a coin toss what her third film will be like, to say nothing of if Gadot will want to keep playing the role afterwards.
We have a long way to go before Diana takes Superman's role as DC's #2. Them resorting to stunts like making Clark black would just be WB/DC trying something else to appeal to people like they've been doing for the past decades with him or Diana. At best, I'd say Clark and Diana are simply sharing the #2 spot as opposed to one replacing the other.