LEGO Star Wars may be introducing more busts to theme, according to speculation from Rebelscum and Stone Wars. The theory is based on rumours that Stone Wars has shared, naming two upcoming sets as follows:
75276 New Adult White, 647 parts
75277 New Adult Green, 625 parts
As Rebelscum points out, previous placeholder names have been mysterious and tricky to figure out, such as Green Seal Leader for Jyn Erso ahead of the Rogue One release. In this case though, the websites suggest that the colours refer to the characters the sets will depict:
75276 Stormtrooper Bust, 647 parts
75277 Boba Fett Bust, 625 parts
While there may be some logic in these suggestions, at the moment this is purely speculation and should be treated as such until more information becomes available.