Nothing is impossible, China phone manufacturer BBK create a thinnest phone record, and it will be broken by itself soon. Some new vivo x3 phone picture leaked on weibo (China Twitter), rumor the thickness is only 5.6mm, less the vivo x2 phone which only 6mm thickness.
Vivo X3 phone will powered a 1.5GHz MTK MT6589T processor, the screen size is larger than 5 inch, with 1080P display, along with 13-megapixel rear camera, and about 2000mAh battery. As report, this new device will unveil in Beijing on August 22th. There is no information about the price tag yet.[source]