I would say some important points would be skill floor for entry, and also either matchmaking, or some other way of getting people who are crap to play other crap people and not get stomped repeatedly. People get put off by being stomped all the time. Inb4 "that compromises the depth of the gameplay", yes, I considered that. But look at the popularity of DTV when it first came out. Inb4 "twas broken"... errr... nope I've got nothing.
Anyhow, I think there is a chance the game could become an esport due to the following features present so far in cRPG:
Melee system is "Easy to learn, hard to master"
So far there is a wave of melee system games, yet none have had the same impact as Warband, so I believe there is still a niche for someone to add to the formula of melee+multiplayer = success. Could be melee + multiplayer + ranking + matchmaking + steam + workshop + twitch + global dedicated servers + localisation = success. (Wouldn't be very expensive at all either
)
Lots of vanity and cosmetic variety
Edit: basically have your core competitive modes, and a couple of fun modes, allow community input and assets for those fun modes, and make it free to play, with an optional singleplayer campaign that people can buy.
Simples!