Well, blackadder is the Chief Executive Creative Writer of the Future Developments Brainstorming department. Has his own office and everything. You never know what may yet manifest if you make him believe… 
I think they’re still experimenting with physical changes. Even then, I doubt it’s wise to go into such specifics as looking like somebody. But things like facial symmetry are not inconceivable.
Same thing for character traits. It is more likely that a sub would be more generic, allowing you to “pick” the traits that you want from multiple people, much like how Bruce Lee took things from multiple martial arts to design JKD.
Instead of creating a “Be more like Johnny Depp” sub (which might even get them sued), they (we?) would create a “Be Your Alter Ego” sub, where you get to design your ideal person through mixing and matching (a supercharger-type thing?) which is then targeted by the subliminal as your goal.