Lucas Black, the actor who had a role in The Fast and the Furious 3: Tokyo Drift, will join the 7th Instalment in order to reprise his role as Sean Boswell. Universal Pictures made a deal with Lucas Black, so he is not only returning for the 7th instalment of the Fast & Furious but at least two more installments (Fast & Furious 8 and 9)
In the Tokyo Drift Sean Boswell ended with Dominic (Vin Diesel) in a race in memory of Han (Sung Kang), who died in the 2nd half of the movie. So, if Sean Boswell was able to prove himself as driver that race, Dom would accept him in the crew and Sean Boswell would be more than inclined to accept that offer.