The new Rumors related to the launch date of Galaxy S4 are placing it at the MWC 2013 (Mobile World Congress) which will take place in Barcelona between 25-28 February next year. This wouldn't be a first for Samsung. They have a habit in using European shows like this one to launch their devices. The Galaxy S3 had the same history. It was first presented in London. And the Galaxy S2 was also presented at the WMC 2011, so the rumor seems plausible.
Other rumors this week were saying that the Galaxy S4 will make its debut at CES in January. So you can see there are still doubts about this issue. Another problem is, that Galaxy S3 has only been out for a few months. So if Galaxy S4 gets out so soon, it will mean that the S3 only had under a year of smartphone domination and people who spent a lot of money to buy it may not like that Samsung is already undermining their phone. Also with the Galaxy S3 being sold in over 30 million units, there may not be so many people who are still willing to spend money on a new Samsung phone.
Samsung's number one enemy, Apple, will also release the iPhone 5S in mid 2013 so maybe Samsung wants to keep up with is main competitor and that's why they are planning this early release of the Galaxy S4.
We'll keep you updated with the latest rumors, so stick around if you want to be the first to know.