The big roller coaster debut at Disneyworld got pushed back to 2023, so they may be waiting until then to announce anything (and or Chapek has mentioned they plan to do another Investor Day but didn't mention when that would be but he gave an inkling that it was possibly the next thing they announce anything at). There was some filming last year at the building that was used for Flynn's Arcade, but it's pretty likely that was for the the Disney ride.
They put at least more than a little effort into a few 40th anniversary events this year, even if their TRON panel at D23 Expo was a snooze. About the only somewhat newsworthy thing was Bruce Boxleitner saying he wasn't planning on doing anything new for TRON going foward. There is also a "thousands of years" after Tron game that was announced at D23.
So in short, I think some continuation is probably happening because otherwise they would just let the brand collect dust, but as to if it's theatrical or D+ unsure, I would be surprised if it significantly features Olivia Wilde & Garrett Hedlund's characters (I was fairly disapointed in Legacy myself, but think they could probably do something worthwhile in another film or D+ series).