The folks over at GSMArena have gotten hold of information on the Galaxy Note 4's display, which they claim was offered by one of their sources. According to a table of info detailing upcoming Samsung phones and tablets, the Galaxy Note 4 – which apparently goes by model number SM-N910, something that was rumored recently – will sport a 5.5-inch display, with a screen resolution of 2560×1440 pixels (QHD). If accurate, the leaked info indicates that Samsung has gone against tradition and decided not to increase the size of the display on its next flagship phablet, which isn't exactly an issue since the 5.7-inch display on the Galaxy Note 3 was among the most sensibly sized display for a phablet.
Another reason for the same screen size might be Samsung's attempts to put a curved display on the Galaxy Note 4, instead of focusing on increasing the screen size and making a not-so-ergonomic smartphone. A curved display isn't going to be on the Galaxy Note 4 for certain, but Samsung has hinted that it is a possibility, and we'll just have to wait and watch what comes to pass on the fourth-generation Galaxy Note.