Use Bungie to make a new single player Killzone campaign? I'd be down for that.
Cuz that's where they were best at doring X360 era and before this BS Destiny was even a thing.
We don't even need to worry about that they'll fuck it up cuz their FPS design skills are one of the best in the industry, so they'll nail that part like it's nothing. As for the story and everything else.... well, Idk. I think they need to go back before the first Killzone and show wtf happened in more detail cuz, I mean, 2 and 3 have great SP campaigns and there's no point in remaking them, so a prequel trilogy I think is the right thing to do here.
If Sony will be smart for once, they'll cancel the goddamn GaaS Marathon nobody asked for and focus on what I just said. It is literally the only way they can save Bungie (if they even want to) and inject new life into them, cuz the way I see it, they are dead otherwise.