Gaunt will be captured by Trazyn the Infinite at some point.
- The Gathering Storm reveals that at least some of Gaunt's Ghosts were captured by the eccentric Necron and added to his collection of Imperial forces. So it is pretty much inevitable that at some point, probably near the end of the Sabbat Worlds' Crusade, the Ghosts will have an unfortunate run in with the Necrons.
- It would make sense for him to take Gaunt as well given how rare the rank of "Colonel-Commissar" is in the Imperial Guard.
- This would also be the perfect way to bring Gaunt into the "present day" Warhammer 40k setting by trapping him in stasis for a couple of centuries.