Unofficial reports surfaced last year stated a high possibility that Bossk will be showing up (along with another character we will mention momentarily).
Bossk has appeared in The Clone Wars, where his character was fleshed out more, but he hasn’t been seen in live-action form since the early trilogy.
Considering Bossk wasn’t seen in the trailer, we’ll have to wait for The Mandalorian’s arrival to see whether the reptilian hunter is involved or not.
The Mandalorian, therefore, would be a good, sensible way to bring Bossk back into the fold, as it wouldn’t be impossible to imagine our new bounty hunter character crossing paths with Pedro Pascal’s titular character.