The level of likelihood that Jet Set Radio 3 (or a JSRF port) will be revealed soon shall henceforth be measured in FUNKCON readiness levels.
FUNKCON 5 is the base, constantly-disappointed-in-Sega state.
FUNKCON 4 is when JSR is mentioned or referenced in other Sega media, for example the Beat outfits in Sonic Forces.
FUNKCON 3 is when new evidence emerges that there were recent attempts at a JSR game underway, indicating Sega may still be accepting ideas for a new game.
FUNKCON 2 would be solid indication that a JSR3 or JSRF port is underway that is still short of an official reveal.
FUNKCON 1 is a real trailer that says “coming soon.”
FUNKCON 0 is when JSR3 is actually revealed to be an ARG, and I get to ride around in roller-skates and vandalize property in real life without getting fatally shot.
FUNKCON ∞ is still classified.