It is quite a rumor at first but one international site got a confirmation on what's next on One Plus
The said smartphone brand confirmed to The Verge that One Plus 5 will be coming as the next flagship phone after the One Plus 3T.
Not a suprise move that there is no One Plus 4 as the said number is unlucky in China, their home turf plus some of their employees were fans of retired NBA player Robert Horry who has the jersey number 5 in the teams that he played
There are also some possibilty that the fifth high-end device from them will be having a dual camera set-up
Source: The Verge