Assuming The Flash stays on Tuesday nights at 8 p.m. in the 2018-2019 season, it will also premiere first of the Arrow-verse shows set on Earth-1.
Perhaps The Flash’s finale airing last of the Earth-1 Arrow-verse shows is just a fluke of CW scheduling and the good guys of The Flash will be able to fix absolutely everything by the end of the finale.
Personally, my fingers are crossed that whatever happens, Mystery Girl is involved.