The new character is confirmed:
https://comicbook.com/tv-shows/news/...showrunner-cw/
There are also two audition videos for Ryan Wilder on Vimeo as of now.
Things to still note: Ryan Wilder has still not been called the lead, whether by the casting call or Caroline Dries, and Kate Kane is not confirmed as being gone for good. I expect they'll do something similar to Bad Blood, where Batman was thought dead for a while.