Other clans might struggle and die out without a clan list, but not XG, we're based around this site. If anything, more people will want to join to enjoy clan matches (ClanCompete) and a highly organized clan/community.
I've played online games before where the community grouped together and developed clan match systems and ladders on their own. XG is already in a position to be able to offer clan structure and clan matches in a game that doesn't offer clans and clan matches.
The H2 clan list was rather limiting, IMO.
That said, I sure could use a larger friends list.