An Imperial Knight detachment is very much outside a normal Foc with only two models being released for the codex. So when new models come out, how will these be handled? and will the foc change to accommodate this? We have a little bit of information regarding this.
Please remember that these are to be considered rumors
via a Forgeworld Response to the Question for the Horus Heresy
We will be producing an update to the Ally Matrix for Horus Heresy with regards to Imperial Knights. At this point in time we can't provide any more information than this.
via a reader here on Faeit 212
I noticed that in the new trailer for Book 3 - Extermination was a picture of how the battle went on the battlefield (about 1:32). There are Imperial Knight icons on this battlefield picture. Maybe this means that we will see Imperial Knights from FW like the rumors are saying, and maybe as soon as this book? Who knows, but interesting nevertheless.
via an anonymous source on Faeit 212
The new Imperial Knights in those rumors are coming later this spring, and we may see our first hints of them at the Forgeworld Open Day.