Regardless of new models or not, it's just so strange the way nurgle was handled in GHB17. There was a quote from Ben Johnson on whtv about Nurgle not being included in GHB17 because they knew Blightwar was coming. If they knew Blightwar (+/- battletome) using combined Nurgle was incoming, why would they divide up Rotbringers and Nurgle daemons separately in the match play profiles (unlike all other Chaos gods, Slaanesh included). Factions had to specify whether they could ally with Rotbringers or Nurgle daemons or both. Seems a real lack of planning; GHB16 felt far more prepared for their upcoming release schedule.
Anyway back to rumours, it's all probably intentional so that people who picked up Blightwar/GHB17 have a reason to pick up a new battletome as well. It's also going to have to immediately errata all the nurgle ally options.