Nope. Making facial expressions to a complexity of every part in the face moveable in a 2D game sounds like an idea that will waste too much time in development and won't even be that much good.
Since you're having portraits come up next to dialog (a good move) then it's good to have facial expressions but to keep them un-animated (like a still picture). Different characters might express facial emotion through different ways. It's good to have a basic face portrait and expressions portraits such as anger, happiness, anxoiusness and sadness. Each character could facially express their emotion in a different way, one character might grit his teeth in anger, while another may just furrow their brow or narrow their eyes.
I also think it'd be a good idea to have a "bloodied" portrait for whenever a character is injured in game but has something to say.
The facial expressions could be used when characters are angry for the sentence that they speak in text boxes.
Ex. *Character A normal portrait* - "So we're leaving for the castle tonight?"
*Character B normal portrait* - "I'm afraid not. We're not leaving until [Character C] recovers from his injuries."
*Character A normal portrait* - "Look. We've had enough distractions, enough detours, enough time wasted."
*Character A angry portrait* - "Enough bullshit, enough everything. We have the oppurtunity to finish this now."
Character A moves towards the door but is blocked by Character B.
*Character A angry portrait * - "Get out of my way."
*Character B anxious portrait* - "..."
*Character B angry portrait* - "You'll have to kill me first."
And then bam, A fight. Or whatever you have in mind.
Of course, if you're thinking of getting voice-actors then forgot animated portraits. There is just so much emotion and expression in voice, coupled with subtitles if that's what you want, that there's no need for something complex like animated portraits or portraits of any kind. The Cat Lady is an amazing game that makes excellent use of voice to convey emotion as well ass body.
Don't forget that there's also emotion in the way a character is presented. Do they puff their chest out confidently in one scene? Is there that spring in their step that signifies a full day? Do they look straight ahead, or do they look down at their feet and have their back hunched like a depressed bastard? Do they step lightly from toe to heel? Do they just stomp around? Do they rub their chin when thinking? Do they bite their nails? Do they always look behind themselves? (Paranoia) Don't forgot about what emotion conveyed tbrough body.