In a game with bows and guns, I can't really see crossbows having enough of a niche to warrant the creation of entirely new skills, especially when theres so much work to do on the game. The idea of lances, and possibly true halberds (they exist in game but don't really look like halberds imo) could be interesting though.
I do feel like they need new weapon classes and abilities that are generic as well as weapon or even shield specific, but it's fairly obvious they'll continue to develop those as time goes on. The introduction of polearms though would give another option for how to play two handed melee. Currently I feel like two handed melee and mages are the most stale game play. Mages are essentially forced to use staves (wands are heavily discussed on the forums) since they're the only weapon that restores willpower, while two handed weapons only have to real classes/styles of auto attack (hammer/axe type, and sword type) with the basic attack really being the only thing that differentiates the two. Since basic attacks are honestly just a way to restore rage/willpower though I can't imagine these issues will be a very high priority since there are so many bugs and graphical issues in the game: ie, falling through floors, getting stuck in walls, enemies falling through maps, etc

TLDR: wouldn't hold my breath on the addition of new weapon types, and if they do add a new weapon wands or another one handed mage item needs to be first but lances/polearms would be cool