Games Workshop posts more evidence of revisions to the lore in the wake of 10th Edition's failure. First they dialed back the severity of Angron's invasion of Armagddon and the damage Chaos had done to the planet. Now the Nauchmund Gauntlet warzone is gone, replaced by the Cadian Gate warzone. This leaves the Bastior (Tyranids) and Pariah Nexus (Necrons) warzones the only two from 10th edition still fully recognized from 10th edition.
It makes sense Nachmund and Angron's invasion would get the axe. Nachmund was just a less impactful redo of Vigilus, and Angron's invasion was equally a badly written rewrite of the 1st War For Armageddon. While they're not 'gone,' they're now severely downplayed.
Possibly cold take/rant: the Primarchs should've stayed in the 30k time period.
Modern 40k felt more engaging when the Loyalists were either missing, inactive or dead, while the Traitors oversaw their plans from the Warp. Them returning en masse screams Horus Heresy 2 to me.