They already do I think? At least the default subreddit list (or whatever it calls - the subreddits shown top of screen) includes swedish subreddits when I'm not logged on.
Yeah, when the new defaults were added 4-ish months ago, they experimented with some country-specific defaults. I think they only set it up for Sweden though.
Edit: Actually, Kenya, Sweden, and Singapore. http://www.reddit.com/r/bugs/comments/27rxzs/strange_subredd...
Maybe use IP address geolocation to suggest subreddits during onboarding?