It's an interesting idea.
How would you set up the articulation on the figure? I guess the arms, head, and upper torso would be set up to current NECA standards, but a seated figure poses its own challenges. Has NECA ever made such a thing as a seated figure? I imagine everything below the waist might have to be fixed immovably into a seating position, maybe? I don't know... I'm thinking it would have to be this way because a proper seating position with knees together is a tight arrangement for articulated figures that otherwise stand naturally.
Vriess does have to abandon the chair at one point, right? That will add quite some challenge to the figure's preparation.
The wheelchair would be an entirely separate item with the wheels fully rotating and the shotgun concealed as separate pieces throughout the chair.
Sure, it would be an interesting challenge, though - if NECA chose to take it on. It could be cool, yeah.
-Windebieste.