Not only would this allow these two characters to carve out their specific niches in the Fast and Furious world; it would also serve to remind longtime fans of the series (those who perhaps feel that the franchise has moved too far away from its origins) that the Fast and Furious films still remember where they come from and are willing to continue embracing street racing as a central motif.
Although the series has gradually moved away from racing as its core concept, Dom (Vin Diesel) and Letty’s (Michelle Rodriguez) connection to the world of street racing continues to play a central role in their respective arcs.
The Cuba opening for Fate proved that.
In that regard, a spin-off movie centering on their life on the road (as well as their attempts to raise Brian Toretto correctly) could easily allow the Fast and Furious franchise to go back to basics by getting them back behind the wheels of some souped-up muscle cars.