With dual camera is the trend for smartphone launched in 2017, looks like 2018 is for the triple camera. According to the source, design for upcoming Huawei P20 series leaks online suggest triple camera on the back.
The alleged image reveal the overall design for P20 series smartphone- a regular P20, P20 Plus, and P20 Pro. All three headset comes with the Triple camera and a report suggest Huawei triple camera smartphone feature 40MP resolution with 5x Hybrid Zoom.
Huawei P20 and P20 PLus have a similar design with a horizontal triple camera and vertical triple camera on the back respectively. Rumors are also that P20 and P20 Plus will be powered by Kirin 970 processor and P20 Pro will be powered with more advanced Kirin 975 processor.
Huawei could possibly unveil these smartphones at MWC 2018, however, a roadmap of Huawei 2018 suggest these devices may be unveiled/launched/announce/available on Q2 of 2018.