Star Trek

Probably. There's nothing said about how active the moderators have to be, and there are a few who would happily claim the role, even if they aren't going to do anything with it, except to step in when other mods do something they dislike (since Reddit's mod privilege system is hierarchical, higher mods outright lower ones, and can remove them if desired). /r/Tumblr basically had that problem, with the only recently active mod being kicked off by both Reddit, and one of the higher moderators, who opened the sub back up (its back private now, citing a "disinformation campaign", so the users probably rioted, given the support for a shut down). There's a suggestion that it was a Reddit scab who suddenly became active, and booted said mod, but that could be either rumour or fact, since there's not a lot of supporting evidence in either direction, except that said user is not on the site, nor moderator on /r/tumblr any longer.

Reddit does have an issue with "power mods", where a user will just collect moderation roles in subreddits, so there are a few who would probably just add a few new subs to the list.

What happens afterwards probably depends on the user base. While they could probably try and silence dissent, no few people can handle multiple riots going across multiple subs they moderate.