MediaTek hardware is a mainstay of lower-end devices, like Nokia's 5.1 Plus / X5 and Oppo's R15, where price is a big factor. This 7-nanometer chip should hopefully offer a decent mix of power efficiency and speed, although don't expect anyone at Qualcomm to feel too worried. The silicon will be available for companies to use at some point before the Fall, with the first releases due at the start of 2020.
Given the relative dearth of companies making 5G hardware, MediaTek's persistence is welcome to avoid the space becoming too small. After all, Qualcomm is almost the only game in town, given that the only other company making 5G modems is Samsung. Intel has recently decided to get out of the space, and Huawei is living in its own world of hurt right about now. MediaTek might wind up becoming the go-to option for many companies who can't, or won't opt, for Qualcomm's technology.