Eh, they're five years too late. This is going to be Slender all over again.
I've been consistently willing to hear it out.
FNAF isn't as much of a dying brand as people are wanting to think it is. Is it as strong as when things began to move? No. But good marketing, a good script, and positive receptions can go a long way for an IP like this being adapted.
Odds are this is Universal. They still have the First Look deal with Blumhouse to 2024 (as far as I'm aware), and I can't see them passing up an IP like Five Nights. Even despite the somewhat faded popularity that it has compared to before-hand.