My current thinking is that Linguist & friends should be converted to backgrounds.
Essentially, the proposal is to add a single "trained background" where a player is allowed to pick a feat (from a list containing Keen Mind, Linguist etc) in return for spinning a tale as to how that character came to that type of specialized training. The feat would be the Feature of that background.
Actor on the other hand is borderline too-strong for this, since getting advantage on deception is close to a free pass on talking your way past guards and such, and can often replace even magic. (Actually, in my review, I gave Actor an overall grade of blue, so I'm definitely planning to let it stand as-is)
So the list definitely contains Keen Mind and Linguist, but that's about it. Observant would be on the list if not for the +5 passive perception (which is very strong, since in practice it means no monster or trap can ever surprise you again).