It's genuine. Nice find!
http://comicbook.com/anime/2018/01/19/dragon-ball-super-anime-ending-2018/
Of course, there is a chance that Dragon Ball will live on in the future. Fuji TV stresses it has no plans to broadcast a new Dragon Ball show at the moment, but it did not sentence the entire series to death. The network stressed the virility of Dragon Ball’s franchise in its announcement by saying “it’s not like the series is over.”
https://kotaku.com/dragon-ball-super-is-ending-this-march-1822219535
Update January 19 - 4:45am: Japanese site Sanspo writes that Dragon Ball Super, the fifth anime in the series, is ending this March, adding that Fuji TV says a new production is currently TBA and that “it’s like not the series is finished.” It’s unclear if, in the Fuji TV quote, “series” refers only to Dragon Ball Super or the entire Dragon Ball anime series.
That image in that twitter link is very basic marketing talk: you don't start talking about the sequel before the original is finished or else you risk shooting yourself in the foot. Nobody believes for one second that there won't be a new Dragon Ball series, including the person who's twitter you're linking.