Man I REALLY enjoyed that! I was so genuinely creeped out once I started realizing what was happening to them. I have some ideas on ending but I'm not exactly sure about them... which is honestly fantastic. I love a story that doesn't spell itself out for you. I'll put thoughts past "spoiler dots" though.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ok hopefully that's enough. My thoughts are that John figured it out in the end after all. He seems to realize some things during his phone call with K, although he doesn't share them with the readers (rude). Personally, I think he realized that remembering the victims and trying to tell others about them is what caused it to spread, and he realized that K was as doomed as the rest of them sooner or later... so he forced her to say her name while on the phone with him to trigger the curse, so she would never have the chance to spread it to others. Then he went to the attic and waited for the thunderclap to signify that K was dead, confirmed that he had no memory of any of the other victims, and died without triggering the curse so that it ended with him.
Too bad for modern technology though, because now it's able to spread again. Damn you, Alan Thomas!
I don't think it can spread again, or at least not easily. It doesn't seem to be enough to remember simply anyone who died, you have to remember specifically the last victim immediately before yourself - somewhat analogous to It Follows. The officer who died isn't known to you the player, and on reading these files, you know enough not to try jog Alan Thomas' memories. It seems Thomas didn't know the officer particularly well, he was an outsider brought in, and Thomas can't put a name or description to him, so it doesn't seem to have kept going.