Like any popular phone, having a recurring line will keep everyone in the wanting mood. On the horizon it seems that "The Next Big Thing" is possibly the Galaxy S4. If you think the Galaxy S3 was just released, you are right, it was. And now they are moving on to a possibly bigger, definitely better unit almost a year later. Heck, that beats Apple by about 2 years!
The Galaxy line of Samsung phones has them ranging from the lowest range to the top-of-the-line tablets and quite literally everything in the middle. While it's not uncommon for a phone to have a successor, it's pretty unique that it happens every year. Some of the key components that they plan to make a tradition are the larger size and the "inspired by nature" design theme.
If the rumors are all true then we will see a screen go from a 4.8" to a 5" screen. The codename rumored for this phone is Project J. We don't know what or if the J is significant to anything or not, previous reports from earlier in the year suggested that Samsung was going to start a new operating system of their own so while it's unlikely, it's not completely excluded from the theory.
Some of the rumors that have come out in the past about Project J are a Full HD AMOLED screen, Quad-core CPU, the latest version of Android and a 13MP camera. All of these are pure speculation right now and none of it is verified. it is nice to see that Samsung, despite the legal battles, is going to keep going without fail to produce the best of the best.