Well it just kind of seems like a copy of M&B multiplayer but with some modernisations (afterall the basics of M&B are almost 10 years old now, and started as an indie garage game). If they do it well it will have a less glitchy melee physics engine, and cRPG-like character customizations built in.
I think they are hoping to bring in new people who haven't really tried M&B, or just getting people who only play native Warband not mods, by showing off its slick features, doing promotions, etc. cuz there isn't too much appeal to existing M&B player communities.
Paradox is hedging tho, they aren't going all-in with War of the Roses, they are still supporting M&B, with stuff like publishing Mount & Musket as Napoleon DLC. I still have a hunch "Project Asinus" is Paradox publishing cRPG in the same sort of deal.