How this will work was not explained, as we were only shown a brief glimpse of concept art featuring Scooby-Doo and some sketches of other Hanna-Barbera characters. The exact quote used in a much longer over-arching WAG sizzle reel was that the film will be “our first shot at unlocking the whole Hanna-Barbera Universe.”
Other Hanna-Barbera properties include The Flintstones, Yogi Bear, The Jetsons, The Smurfs, Top Cat, Jonny Quest, Wacky Races, Sealab 2020, and many other cartoons, although some of those, like the Smurfs, are owned elsewhere and obviously couldn’t be part of this cinematic universe. There’s also the question of if and how they might cross over, considering they all take place in different settings and time periods. Aside from S.C.O.O.B., the studio has not announced release dates for any of other Hanna-Barbera movies.