Is a Canon RF 200-500mm f/5.6L IS USM a possibility?

We have been reporting for what seems an eternity that Canon will be announcing an RF 200-500mm f/4L IS USM any day now! That has obviously has not come to pass, but over the last month or two there have been some changes in what the 200-500 may actually be. Sometimes information has some assumptions, and sometimes we’re guilty of the same thing (insert the quote).