Rakeysh Omprakash Mehra and Farhan Akhtar Reunite for a movie

This is what Farhan was talking about.

IT'S OFFICIAL... After #BhaagMilkhaBhaag, Rakeysh Omprakash Mehra and Farhan Akhtar reunite for #Toofan... A heartfelt story of a boxer... Mehra will direct the film.
https://twitter.com/taran_adarsh/status/1085393537955479552?s=21

So this was Farhan's big announcement not Don 3. Media went on an overdrive thinking that he was talking about Don 3 to the extent of spreading rumours that SRK walked out of SJSA.