According to The Korea Times, who received confirmation from an executive at one of Samsung's supplier partners, both devices are to be made available and will be announced at IFA 2014 in September.
The curved device may see a limited release in selected markets, though they haven’t been specified, while the regular flat faced device will get a more widespread launch. There is always the possibility that the curved Galaxy Note 4 would be released in more territories at a later date.
Other rumours suggest that the Galaxy Note 4 will feature a 5.7-inch display with a QHD resolution of 2,560 x 1,440. It will have a 2.7GHz Qualcomm Snapdragon 805 and 4G RAM, while it’s suggested that it’ll pack a 16 megapixel camera with optical image stabilization.