There's a possibility that it's not coming to Steam. Ever.
Epic is acting as the publisher and they funded the development of the game. However there's always the possibility of Alan Wake 2 not selling well enough on EGS so Epic decided to put the game on Steam to recoup the costs.
Control ended up being given away through Amazon gaming and Epic, so even if it never comes to Steam if willing to wait it might be attainable legally without paying. I haven't played the Dead Space or Resident Evil 4 Remake yet so got lot of other games ahead of it that are cheaper than the $60 asking price and hardware requirements.
I played both Alan Wake and American Nightmare, interesting story but didnt love them, probably not my kind of game. Control blew me away, though, so now I'm wondering...