I see a lot of confusion on this subreddit in regards to the release of MS2. I just want to make it clear that there is a confirmed worldwide release. No, this doesn't mean Korea will have a release first and other countries will see it in the years to come. It means once the final game is fully enabled for release, it will be released everywhere that Nexon and its coworkers are planning on releasing MS2 to. Yes, Korea will be the only ones to receive a beta, which is set for mid 2015.
So to clear it up, Nexon has already clarified that Maplestory 2 will see a worldwide release. If you want proof, just google "Maplestory 2 worldwide release". You will find several articles.
Definition of worldwide release at this point isn't very correct. Mainly it's all coming out on the same day, as in for example January 4th, 2016; but when the various countries get their 1/6/16 to come around, the other side of the world would be at 1/7/16.
A "true" worldwide release is all the servers going live at the same exact time, give or take a couple seconds/minutes. Either way, we'll be pretty much getting it a couple hours after the rest of the world does, knowing Nexon they'll probably botch something and have to have an SM which could backlog the game some 12 hours at most (like quite a few times in MS 1 where the problem was a simple fix and they break a whole bunch of things that it took little over 12 hours to fix, which also cut into some of the events that they didn't bother reimbursing for some players.
I saw the "worldwide release schedule will be confirmed at a later date" letter from Nexon's PR team but that can mean so many different things.
The Investor's Presentation that is published on Nexon's IR page: http://ir.nexon.co.jp/en/ states that only Dirty Bomb and some mobile games are scheduled for North America.
The only mention of Maplestory 2 is that it is being developed "in-house" in Korea.
The Quarter 1 results of 2015 might change the schedules quite a bit but we will have to see on May 14, when that is released to the public.