Apparently third person will be an option on unofficial servers. Interestingly, it seems the Chivalry and Mordhau communities absolutely hate third person and relate it to cheating since it gives an advantage over first person players. I don't think it will be that difficult to get used to, Chivalry and Warband had distinct enough combat systems that I always felt they didn't overlap. I never felt like I had an advantage in Chivalry because I played Warband, but neither did I feel hindered by it.
The small infantry battles are looking great, they removed the exploits from the combat system while adding to the complexity. The fights look fast and skillful, while not feeling unfair or looking stupid like they often did in Chivalry. Larger infantry fights always felt clunky to me in Chivalry just because of how blocking works, and I'm getting the same vibe from Mordhau.
Cavalry looks pretty rough in this trailer. It might just be in an early state, but I hope it eventually becomes a meaningful part of the game like in Warband, and not something rushed into the game because of popular demand.