Would love to see an Eldar exile as a replacement for Kerillian and/or an assassin or imperial death cult specialist of some sort. I imagine the Eldar exile to play similarly to Waystalker and the Assassin to play very much like shade. The option of a melee only character could still work well with the inclusion of riot/storm shields and multiple grenade slots.
Wouldn’t mind seeing some of the weapon patterns from Vermintide 2 being carried over. Could definitely see the 2handed hammer with slower attack speed and more damage work as the thunder hammer.
As for alien weapons, we could have alien characters, the inquisitor could use some and we could see a rogue trader character. No reason an inquisitor and trader wouldn’t team up to recover some artifacts from the hive.