I am assuming nothing. Lynne was the true Seer and her visions did not lie. Kimblee and his partner are soulbonded demons, there is no doubt of that.

[ They could be Sinners and Kimblee's just the supremest jackass of them all, but Oswin will eat the hat he doesn't own if it's really a coincidence that Lynne told Kimblee her role and then died the same night. ]

It is probably prudent to keep an eye on her, then.