Sounds like a great choice that the final book of the Horus Heresy called the Siege of Terra will be written by Dan Abnett.
Here is what I was just told.
via our friends over on La Voz de Horus
https://www.lavozdehorus.com/dan-abnett-podria-ser-el-autor-
We have two independent sources that have spoken with Dan Abnett. Both sources report the same new: Abnett will be the author of the final book of Horus Heresy: Siege of Terra.
We posted it in our site, with more known info about Siege of Terra and Horus Heresy, but the important part is that Abnett will do the final Emperor vs Horus battle:
