Well, Halo 4 is supposed to come out this year, but to me it feels so soon. It was just announced last year, about 7 months ago. And Reach has barely been out for almost a year in a half.
I like the idea that 343 has to delve out the forerunners and go more into the history of the forerunners, but I also kinda don't like that. Because i like that sense of mystery in previous Halo games, for example the terminals in Halo 3. I liked having little knowledge, which made the forerunners seem....so mysterious I guess. But now in Halo 4, a lot more is to be said about them.
Also I haven't read Primordium yet or any of the forerunner books yet.