Walmart Canada had a leak about a month ago where it had a list of titles that was scheduled as E3 announcements outed prematurely. Following that Leak, Bethesda came out and officially confirmed Rage 2. The Walmart list also included Just Cause 4 but Square Enix has been extremely tight lipped about it most likely due to them having their first E3 Conference again in a long time and that is most likely one of the headline titles for the conference along with Shadow of the Tomb Raider.
That Reveal might have been spoiled though as user who logged into steam last night were greeted with this.
Which is an unnoficial but official confirmation that the title is legit will be released on PC and that we will definately be seeing it at E3 2018.
Square Enix is yet to respond but since E3 is mere days away they'll probably just hold out with the trailer until then.