It looks like Samsung Galaxy S4 sales are much weaker than Samsung initially predicted. They had to revise their estimates for May, and reduce them by 50% down to 6.5 Million units. Ironically, part of the reason is that more folks are opting instead to buy the now cheaper Samsung Galaxy S3, which is something Samsung apparently didn't account enough for. Perhaps it is a good problem to have from one point of view. On the other hand, competing with yourself doesn't always work out in the business world.
To boost sales of the SGS4, Samsung intends to retire the SGS3 a bit earlier than expected. On the slip-side of this, Samsung will move up the launch of the Samsung Galaxy Note 3 a bit earlier in order to give themselves an overall boost in mobile sales. This will also potentially give them a leg up on sales by getting their phablet to market quicker than HTC's T6. Additionally, it will offer consumers another Samsung alternative a bit before the announcement of the iPhone 5S.
Additionally, the pic above is supposedly a leaked peek at the new GNote3 from Samsung, although it does contradict some earlier leaks and could not be corroborated.
Source: PhoneArena