Mozilla plans to roll version 70 during October 23, 2019 according to the release schedule.

The release of Firefox 57 re-titled the browser to Quantum to push new technologies in the browser to improve all aspects of Firefox and reverse the downwards trend user-wise. Starting with Firefox 70, the new name is Firefox Browser.   Plain Firefox would not make much sense anymore either because of other projects that carry the Firefox brand. Mozilla launched plenty including Firefox MonitorFirefox Send or Firefox Lockwise in recent years and plans to launch even more, e.g. Firefox Proxy, in the future.